1.1   License

SIP is licensed under the same terms as Python itself. SIP places no restrictions on the license you may apply to the bindings you create.

1.2   Features

SIP, and the bindings it produces, have the following features.

• bindings are fast to load and minimise memory consumption especially when only a small sub-set of a large library is being used
• automatic conversion between standard Python and C/C++ data types
• overloading of functions and methods with different argument signatures
• access to a C++ class's protected methods
• the ability to define a Python class that is a sub-class of a C++ class, including abstract C++ classes
• support for ordinary C++ functions, class methods, static class methods, virtual class methods and abstract class methods
• the ability to re-implement C++ virtual and abstract methods in Python
• support for global and class variables
• support for C++ namespaces
• support for C++ exceptions and wrapping them as Python exceptions
• the ability to define mappings between C++ classes and similar Python data types that are automatically invoked
• the ability to automatically exploit any available run time type information to ensure that the class of a Python instance object matches the class of the corresponding C++ instance
• full support of the Python interpreter lock, including the ability to specify that a C++ function of method may block, therefore allowing the lock to be released and other Python threads to run
• support for the concept of ownership of a C++ instance (i.e. what part of the code is responsible for calling the instance's destructor) and how the ownership may change during the execution of an application
• the ability to generate bindings for a C++ class library that itself is built on another C++ class library which also has had bindings generated so that the different bindings integrate and share code properly
• a sophisticated versioning system that allows the full lifetime of a C++ class library, including any platform specific or optional features, to be described in a single set of specification files
• the ability to include documentation in the specification files which can be extracted and subsequently processed by external tools
• the ability to include copyright notices and licensing information in the specification files that is automatically included in all generated source code
• a build system, written in Python, that you can extend to configure, compile and install your own bindings without worrying about platform specific issues
• SIP, and the bindings it produces, runs under UNIX, Linux, Windows and MacOS/X

SIP also understands the signal/slot type safe callback mechanism implemented by Qt. SIP allows new Python signals to be defined, and allows any Python callable object to be used as a slot.

1.3   SIP v3.x

SIP v3.x differs from current versions in the following respects.

• It uses Python's classic classes to wrap C++ classes (and so generated bindings can be built against any version of Python).
• It does not support the creation of bindings for C libraries.
• It does not generate bindings that will work on MacOS/X.
• It is not formally documented. However, most of this document does apply to SIP v3.x - just don't be surprised if you come across something that doesn't.

New releases of SIP v3.x may be made in the future, but no significant development will be done.

1.4   SIP Components

SIP comprises a number of different components.

• The SIP code generator (sip or sip.exe). This processes .sip specification files and generates C or C++ bindings. It is covered in detail in Using SIP.
• The SIP header file (sip.h). This contains definitions and data structures needed by the generated C and C++ code.
• The SIP module (sip.so or sip.pyd). This is a Python extension module that is imported automatically by SIP generated bindings and provides them with some common utility functions. See also Using the SIP Module in Applications.
• The SIP build system (sipconfig.py). This is a pure Python module that is created when SIP is configured and encapsulates all the necessary information about your system including relevant directory names, compiler and linker flags, and version numbers. It also includes several Python classes and functions which help you write configuration scripts for your own bindings. It is covered in detail in The SIP Build System.

2.1   Downloading SIP

You can get the latest release of the SIP source code from http://www.riverbankcomputing.co.uk/sip/download.php.

SIP is also included with all of the major Linux distributions. However, it may be a version or two out of date.

You may also find more up to date pre-compiled binaries on SourceForge.

2.2   Configuring SIP

After unpacking the source package (either a .tar.gz or a .zip file depending on your platform) you should then check for any README files that relate to your platform.

Next you need to configure SIP by executing the configure.py script. For example:

python configure.py

This assumes that the Python interpreter is on your path. Something like the following may be appropriate on Windows:

c:\python23\python configure.py

If you have multiple versions of Python installed then make sure you use the interpreter for which you wish SIP to generate bindings for.

Qt support is automatically enabled if the QTDIR environment variable is set. Use the -x command line option to disable it.

The full set of command line options is:

The configure.py script takes many other options that allows the build system to be finely tuned. These are of the form name=value or name+=value. The -h option will display each supported name, although not all are applicable to all platforms.

The name=value form means that value will replace the existing value of name.

The name+=value form means that value will be appended to the existing value of name.

For example, the following will reduce the size of module binaries compiled with GCC:

python configure.py CXXFLAGS+=-fno-exceptions LFLAGS+=-s

A pure Python module called sipconfig.py is generated by configure.py. This defines each name and its corresponding value. Looking at it will give you a good idea of how the build system uses the different options. It is covered in detail in The SIP Build System.

c:\python23\python configure.py -p win32-g++

c:\python23\python configure.py -p win32-borland

coff2omf python23.lib python23_bcpp.lib

2.3   Building SIP

The next step is to build SIP by running your platform's make command. For example:

make

The final step is to install SIP by running the following command:

make install

(Depending on your system you may require root or administrator privileges.)

This will install the various SIP components.

3.1   A Simple C++ Example

We start with a simple, but complete, example. Let's say you have a C++ library that implements a single class called Word. The class has one constructor that takes a \0 terminated character string as its single argument. The class has one method called reverse() which takes no arguments and returns a \0 terminated character string. The interface to the class is defined in a header file called word.h which might look something like this:

// Define the interface to the word library.

class Word {
    const char *the_word;

public:
    Word(const char *w);

    char *reverse() const;
};

The corresponding SIP specification file would then look something like this:

// Define the SIP wrapper to the word library.

%Module word 0

class Word {

%TypeHeaderCode
#include <word.h>
%End

public:
    Word(const char *);

    char *reverse() const;
};

Obviously a SIP specification file looks very much like a C++ (or C) header file, but SIP does not include a full C++ parser. Let's look at the differences between the two files.

• The %Module directive has been added ¹. This is used to name the Python module that is being created and to give it a generation number. In this example these are word and 0 respectively. The generation number is effectively the version number of the module.
• The %TypeHeaderCode directive has been added. The text between this and the following %End directive is included literally in the code that SIP generates. Normally it is used, as in this case, to #include the corresponding C++ (or C) header file ².
• The declaration of the private variable this_word has been removed. SIP does not support access to either private or protected instance variables.
• The name of the argument to the constructor has been removed. SIP does not support named arguments ³.

If we want to we can now generate the C++ code in the current directory by running the following command:

sip -c . word.sip

However, that still leaves us with the task of compiling the generated code and linking it against all the necessary libraries. It's much easier to use the SIP build system to do the whole thing.

Using the SIP build system is simply a matter of writing a small Python script. In this simple example we will assume that the word library we are wrapping and it's header file are installed in standard system locations and will be found by the compiler and linker without having to specify any additional flags. In a more realistic example your Python script may take command line options, or search a set of directories to deal with different configurations and installations.

This is the simplest script (conventionally called configure.py):

import os
import sipconfig

# The name of the SIP build file generated by SIP and used by the build
# system.
build_file = "word.sbf"

# Get the SIP configuration information.
config = sipconfig.Configuration()

# Run SIP to generate the code.
os.system(" ".join([config.sip_bin, "-c", ".", "-b", build_file, "word.sip"]))

# Create the Makefile.
makefile = sipconfig.SIPModuleMakefile(config, build_file)

# Add the library we are wrapping.  The name doesn't include any platform
# specific prefixes or extensions (e.g. the "lib" prefix on UNIX, or the
# ".dll" extension on Windows).
makefile.extra_libs = ["word"]

# Generate the Makefile itself.
makefile.generate()

Hopefully this script is self-documenting. The key parts are the Configuration and SIPModuleMakefile classes. The build system contains other Makefile classes, for example to build programs or to call other Makefiles in sub-directories.

After running the script (using the Python interpreter the extension module is being created for) the generated C++ code and Makefile will be in the current directory.

To compile and install the extension module, just run the following commands ⁴:

make
make install

That's all there is to it.

3.2   A Simple C Example

Let's now look at a very similar example of wrapping a C library:

/* Define the interface to the word library. */

struct Word {
    const char *the_word;
};

struct Word *create_word(const char *w);
char *reverse(struct Word *word);

The corresponding SIP specification file would then look something like this:

/* Define the SIP wrapper to the word library. */

%CModule word 0

struct Word {

%TypeHeaderCode
#include <word.h>
%End

    const char *the_word;
};

struct Word *create_word(const char *);
char *reverse(struct Word *);

Again, let's look at the differences between the two files.

• The %CModule directive has been added. This has the same syntax as the %Module directive used in the previous example but tells SIP that the library being wrapped is implemented in C rather than C++.
• The %TypeHeaderCode directive has been added.
• The names of the arguments to the functions have been removed.

The configure.py build system script described in the previous example can be used for this example without change.

3.3   A More Complex C++ Example

In this last example we will wrap a C++ library that contains a class that is derived from a Qt class. This will demonstrate how SIP allows a class hierarchy to be split across multiple Python extension modules, and will introduce SIP's versioning system.

The library contains a single C++ class called Hello which is derived from Qt's QLabel class. It behaves just like QLabel except that the text in the label is hard coded to be Hello World. To make the example more interesting we'll also say that the library only supports Qt v3.0 and later, and also includes a function called setDefault() that is not implemented in the Windows version of the library.

The hello.h header file looks something like this:

// Define the interface to the hello library.

#include <qlabel.h>
#include <qwidget.h>
#include <qstring.h>

class Hello : public QLabel {
    // This is needed by the Qt Meta-Object Compiler.
    Q_OBJECT

public:
    Hello(QWidget *parent, const char *name = 0, WFlags f = 0);

private:
    // Prevent instances from being copied.
    Hello(const Hello &);
    Hello &operator=(const Hello &);
};

#if !defined(Q_OS_WIN)
void setDefault(const QString &def);
#endif

The corresponding SIP specification file would then look something like this:

// Define the SIP wrapper to the hello library.

%Module hello 0

%Import qt/qtmod.sip

%If (Qt_3_0_0 -)

class Hello : QLabel {

%TypeHeaderCode
#include <hello.h>
%End

public:
    Hello(QWidget * /TransferThis/, const char * = 0, WFlags = 0);

private:
    Hello(const Hello &);
};

%If (!WS_WIN)
void setDefault(const QString &);
%End

%End

Again we look at the differences, but we'll skip those that we've looked at in previous examples.

• The %Import directive has been added to specify that we are extending the class hierarchy defined in the file qt/qtmod.sip. This file is part of PyQt. The build system will take care of finding the file's exact location.
• The %If directive has been added to specify that everything ⁵ up to the matching %End directive only applies to Qt v3.0 and later. Qt_3_0_0 is a tag defined in qtmod.sip ⁶ using the %Timeline directive. %Timeline is used to define a tag for each version of a library's API you are wrapping allowing you to maintain all the different versions in a single SIP specification. The build system provides support to configure.py scripts for working out the correct tags to use according to which version of the library is actually installed.
• The public keyword used in defining the super-classes has been removed. This is not supported by SIP.
• The TransferThis annotation has been added to the first argument of the constructor. It specifies that if the argument is not 0 (i.e. the Hello instance being constructed has a parent) then ownership of the instance is transferred from Python to C++. It is needed because Qt maintains objects (i.e. instances derived from the QObject class) in a hierachy. When an object is destroyed all of its children are also automatically destroyed. It is important, therefore, that the Python garbage collector doesn't also try and destroy them. This is covered in more detail in Ownership of Objects. SIP provides many other annotations that can be applied to arguments, functions and classes. Multiple annotations are separated by commas. Annotations may have values.
• The = operator has been removed. This operator is not supported by SIP.
• The %If directive has been added to specify that everything up to the matching %End directive does not apply to Windows. WS_WIN is another tag defined by PyQt, this time using the %Platforms directive. Tags defined by the %Platforms directive are mutually exclusive, i.e. only one may be valid at a time ⁷.

One question you might have at this point is why bother to define the private copy constructor when it can never be called from Python? The answer is to prevent the automatic generation of a public copy constructor.

We now look at the configure.py script. This is a little different to the script in the previous examples for two related reasons.

Firstly, PyQt includes a pure Python module called pyqtconfig that extends the SIP build system for modules, like our example, that build on top of PyQt. It deals with the details of which version of Qt is being used (i.e. it determines what the correct tags are) and where it is installed. This is called a module's configuration module.

Secondly, we generate a configuration module (called helloconfig) for our own hello module. There is no need to do this, but if there is a chance that somebody else might want to extend your C++ library then it would make life easier for them.

Now we have two scripts. First the configure.py script:

import os
import sipconfig
import pyqtconfig

# The name of the SIP build file generated by SIP and used by the build
# system.
build_file = "hello.sbf"

# Get the PyQt configuration information.
config = pyqtconfig.Configuration()

# Get the extra SIP flags needed by the imported qt module.  Note that
# this normally only includes those flags (-x and -t) that relate to SIP's
# versioning system.
qt_sip_flags = config.pyqt_qt_sip_flags

# Run SIP to generate the code.  Note that we tell SIP where to find the qt
# module's specification files using the -I flag.
os.system(" ".join([config.sip_bin, "-c", ".", "-b", build_file, "-I", config.pyqt_sip_dir, qt_sip_flags, "hello.sip"]))

# We are going to install the SIP specification file for this module and
# its configuration module.
installs = []

installs.append(["hello.sip", os.path.join(config.default_sip_dir, "hello")])

installs.append(["helloconfig.py", config.default_mod_dir])

# Create the Makefile.  The QtModuleMakefile class provided by the
# pyqtconfig module takes care of all the extra preprocessor, compiler and
# linker flags needed by the Qt library.
makefile = pyqtconfig.QtModuleMakefile(
    configuration=config,
    build_file=build_file,
    installs=installs
)

# Add the library we are wrapping.  The name doesn't include any platform
# specific prefixes or extensions (e.g. the "lib" prefix on UNIX, or the
# ".dll" extension on Windows).
makefile.extra_libs = ["hello"]

# Generate the Makefile itself.
makefile.generate()

# Now we create the configuration module.  This is done by merging a Python
# dictionary (whose values are normally determined dynamically) with a
# (static) template.
content = {
    # Publish where the SIP specifications for this module will be
    # installed.
    "hello_sip_dir":    config.default_sip_dir,

    # Publish the set of SIP flags needed by this module.  As these are the
    # same flags needed by the qt module we could leave it out, but this
    # allows us to change the flags at a later date without breaking
    # scripts that import the configuration module.
    "hello_sip_flags":  qt_sip_flags
}

# This creates the helloconfig.py module from the helloconfig.py.in
# template and the dictionary.
sipconfig.create_config_module("helloconfig.py", "helloconfig.py.in", content)

Next we have the helloconfig.py.in template script:

import pyqtconfig

# These are installation specific values created when Hello was configured.
# The following line will be replaced when this template is used to create
# the final configuration module.
# @SIP_CONFIGURATION@

class Configuration(pyqtconfig.Configuration):
    """The class that represents Hello configuration values.
    """
    def __init__(self, sub_cfg=None):
        """Initialise an instance of the class.

        sub_cfg is the list of sub-class configurations.  It should be None
        when called normally.
        """
        # This is all standard code to be copied verbatim except for the
        # name of the module containing the super-class.
        if sub_cfg:
            cfg = sub_cfg
        else:
            cfg = []

        cfg.append(_pkg_config)

        pyqtconfig.Configuration.__init__(self, cfg)

class HelloModuleMakefile(pyqtconfig.QtModuleMakefile):
    """The Makefile class for modules that %Import hello.
    """
    def finalise(self):
        """Finalise the macros.
        """
        # Make sure our C++ library is linked.
        self.extra_libs.append("hello")

        # Let the super-class do what it needs to.
        pyqtconfig.QtModuleMakefile.finalise(self)

Again, we hope that the scripts are self documenting.

3.4   Ownership of Objects

When a C++ instance is wrapped a corresponding Python object is created. The Python object behaves as you would expect in regard to garbage collection - it is garbage collected when its reference count reaches zero. What then happens to the corresponding C++ instance? The obvious answer might be that the instance's destructor is called. However the library API may say that when the instance is passed to a particular function, the library takes ownership of the instance, i.e. responsibility for calling the instance's destructor is transferred from the SIP generated module to the library.

The TransferThis, Transfer and TransferBack annotations are used to specify where, and it what direction, transfers of ownership happen. It is very important that these are specified correctly to avoid crashes (where both Python and C++ call the destructor) and memory leaks (where neither Python and C++ call the destructor).

This applies equally to C structures where the structure is returned to the heap using the free() function.

See also sipTransfer().

5.1   Syntax Definition

The following is a semi-formal description of the syntax of a specification file.

specification ::= {module-statement}

module-statement ::= [module-directive | statement]

module-directive ::= [%CModule | %Copying | %Doc |
        %ExportedDoc | %Feature | %Import | %Include |
        %License | %MappedType %Module | %ModuleCode |
        %ModuleHeaderCode | %OptionalInclude | %Platforms |
        %PostInitialisationCode | %Timeline]

statement :: [class-statement | function | variable]

class-statement :: [%If | class | enum | namespace |
        opaque-class | struct | typedef]

class ::= class name [: super-classes] [class-annotations]
        { {class-line} };

super-classes ::= name [, super-classes]

class-line ::= [class-statement | %ConvertToSubClassCode |
        %ConvertToTypeCode | %TypeCode | %TypeHeaderCode |
        constructor | destructor | method | static-method |
        virtual-method | special-method | operator |
        class-variable | public: | public slots: |
        protected: | protected slots: | private: |
        private slots: | signals:]

constructor ::= name ( [argument-list] ) [exceptions]
        [function-annotations] [c++-constructor-signature] ;
        [%MethodCode]

c++-constructor-signature ::= [( [argument-list] )]

destructor ::= [virtual] ~ name () [exceptions]
        [function-annotations] ; [%MethodCode]
        [%VirtualCatcherCode]

method ::= type name ( [argument-list] ) [const]
        [exceptions] [= 0] [function-annotations] [c++-signature]
        ; [%MethodCode]

c++-signature ::= [ type ( [argument-list] )]

static-method ::= static function

virtual-method ::= virtual type name ( [argument-list] )
        [const] [exceptions] [= 0] [function-annotations]
        [c++-signature] ; [%MethodCode] [%VirtualCatcherCode]

special-method ::= type special-method-name
        ( [argument-list] ) [function-annotations] ;
        [%MethodCode]

special-method-name ::= [ __add__ | __and__ | __call__ |
        __cmp__ | __contains__ | __delitem__ | __div__ |
        __eq__ | __ge__ | __getitem__ | __gt__ |
        __iadd__ | __iand__ | __idiv__ | __ilshift__ |
        __imod__ | __imul__ | __int__ | __invert__ |
        __ior__ | __irshift__ | __isub__ | __ixor__ |
        __le__ | __len__ | __lshift__ | __lt__ |
        __mod__ | __mul__ | __ne__ | __neg__ |
        __nonzero__ | __or__ | __repr__ | __rshift__ |
        __setitem__ | __str__ | __sub__ | __unicode__ |
        __xor__]

operator ::= type operator operator-name
        ( [argument-list] ) [const] [exceptions]
        [function-annotations] ; [%MethodCode]

operator-name ::= [+ | - | * | / | % | & |
        | | ^ | << | >> | += | -= | *= |
        /= | %= | &= | |= | ^= | <<= | >>= |
        ~ | () | [] | < | <= | == | != |
        > | >>=]

class-variable ::= [static] variable

enum ::= enum [name] { {enum-line} };

enum-line ::= [%If | name]

function ::= type name ( [argument-list] ) [exceptions]
        [function-annotations] ; [%MethodCode]

namespace ::= namespace name { {namespace-line} };

namespace-line ::= statement

opaque-class ::= class scoped-name ;

struct ::= struct name { {class-line} };

typedef ::= typedef [typed-name | function-pointer] ;

variable::= typed-name ; [%AccessCode]

exceptions ::= throw ( [exception-list] )

exception-list ::= scoped-name [, exception-list]

argument-list ::= argument [, argument-list]

argument ::= [type [argument-annotations] [default-value] | 
        SIP_QOBJECT | SIP_RXOBJ_CON | SIP_RXOBJ_DIS | SIP_SIGNAL |
        SIP_SLOT | SIP_SLOT_CON()_ | SIP_SLOT_DIS()_]

default-value ::= = expression

expression ::= [value | value binary-operator expression]

value ::= [unary-operator] simple-value

simple-value ::= [scoped-name | function-call | real-value |
        integer-value | boolean-value | string-value |
        character-value]

typed-name::= type name

function-pointer::= type (* name )( [type-list] )

type-list ::= type [, type-list]

function-call ::= scoped-name ( [value-list] )

value-list ::= value [, value-list]

real-value ::= a floating point number

integer-value ::= a number

boolean-value ::= [true | false]

string-value ::= " {character} "

character-value ::= ` character `

unary-operator ::= [! | ~ | - | +]

binary-operator ::= [- | + | * | / | & | |]

argument-annotations ::= see Argument Annotations

class-annotations ::= see Class Annotations

function-annotations ::= see Function Annotations

type ::= [const] base-type {*} [&]

type-list ::= type [, type-list]

base-type ::= [scoped-name | template | struct scoped-name |
        short | unsigned short | int | unsigned |
        unsigned int | long | unsigned long | float |
        double | bool | char | unsigned char | void |
        SIP_PYCALLABLE | SIP_PYDICT | SIP_PYLIST | SIP_PYOBJECT |
        SIP_PYSLICE | SIP_PYTUPLE]

scoped-name ::= name [:: scoped-name]

template ::= scoped-name < type-list >

name ::= _A-Za-z {_A-Za-z0-9}

Here is a short list of differences between C++ and the subset supported by SIP that might trip you up.

• SIP does not support the use of [] in types. Use pointers instead.
• operator can only be used in a class.
• Variables declared outside of a class are effectively read-only.
• Functions and methods do not support argument names.
• A class's list of super-classes doesn't not include any access specifier (e.g. public).

5.2   Additional SIP Types

SIP supports a number of additional data types that can be used in Python signatures.

bool connectItem(int id, const QObject *receiver, const char *member);

bool connectItem(int, SIP_RXOBJ_CON, SIP_SLOT_CON(int));

6.1   %AccessCode

%AccessCode
    code
%End

This directive is used immediately after the declaration of an instance of a wrapped class or structure, or a pointer to such an instance. You use it to provide handwritten code that overrides the default behaviour.

For example:

class Klass;

Klass *klassInstance;
%AccessCode
    // In this contrived example the C++ library we are wrapping defines
    // klassInstance as Klass ** (which SIP doesn't support) so we
    // explicitly dereference it.
    if (klassInstance && *klassInstance)
        return *klassInstance;

    // This will get converted to None.
    return 0;
%End

6.2   %CModule

%CModule name [version]

This directive is used to identify that the library being wrapped is a C library and to define the name of the module and it's optional version number.

See the %Module directive for an explanation of the version number.

For example:

%CModule dbus 1

6.3   %ConvertFromTypeCode

%ConvertFromTypeCode
    code
%End

This directive is used as part of the %MappedType directive to specify the handwritten code that converts an instance of a mapped type to a Python object.

The following variables are made available to the handwritten code:

type *sipCpp

This is a pointer to the instance of the mapped type to be converted. It may be zero.

The handwritten code must explicitly return a PyObject *. If there was an error then a Python exception must be raised and NULL returned.

The following example converts a QValueList<int> instance to a Python list of numbers:

%ConvertFromTypeCode
    // Handle the case where the C++ instance is 0.
    if (!sipCpp)
        return PyList_New(0);

    PyObject *l;

    // Create the Python list of the correct length.
    if ((l = PyList_New(sipCpp -> count())) == NULL)
        return NULL;

    // Go through each int in the C++ instance and convert it to a number.
    for (uint i = 0; i < sipCpp -> count(); ++i)
        if (PyList_SetItem(l, i, PyInt_FromLong((*sipCpp)[i])) < 0)
        {
            // There was an error so garbage collect the Python list.
            Py_DECREF(l);
            return NULL;
        }

    // Return the Python list.
    return l;
%End

6.4   %ConvertToSubClassCode

%ConvertToSubClassCode
    code
%End

When SIP needs to wrap a C++ class instance it first checks to make sure it hasn't already done so. If it has then it just returns a new reference to the corresponding Python object. Otherwise it creates a new Python object of the appropriate type. In C++ a function may be defined to returned an instance of a certain class, but can often return a sub-class instead.

This directive is used to specify handwritten code that exploits any available real-time type information (RTTI) to see if there is a more specific Python type that can be used when wrapping the C++ instance. The RTTI may be provided by the compiler or by the C++ instance itself.

The directive is included in the specification of one of the classes that the handwritten code handles the type conversion for. It doesn't matter which one, but a sensible choice would be the one at the root of that class hierarchy in the module.

Note that if a class hierarchy extends over a number of modules then this directive should be used in each of those modules to handle the part of the hierarchy defined in that module. SIP will ensure that the different pieces of code are called in the right order to determine the most specific Python type to use.

The following variables are made available to the handwritten code:

type *sipCpp

This is a pointer to the C++ class instance.

sipWrapperType *sipClass

The handwritten code must set this to the SIP generated Python type object that corresponds to the class instance. (The type object for class Klass is sipClass_Klass.) If the RTTI of the class instance isn't recognised then sipClass must be set to NULL.

The handwritten code must not explicitly return.

The following example shows the sub-class conversion code for QEvent based class hierarchy in PyQt:

class QEvent
{
%ConvertToSubClassCode
    // QEvent sub-classes provide a unique type ID.
    switch (sipCpp -> type())
    {
    case QEvent::Timer:
        sipClass = sipClass_QTimerEvent;
        break;

    case QEvent::KeyPress:
    case QEvent::KeyRelease:
        sipClass = sipClass_QKeyEvent;
        break;

    // Skip the remaining event types the keep the example short.

    default:
        // We don't recognise the type.
        sipClass = NULL;
    }
%End

    // The rest of the class specification.

};

The SIP API includes the sipMapIntToClass() and sipMapStringToClass() functions that convert integer and string based RTTI to Python type objects based on ordered lookup tables.

6.5   %ConvertToTypeCode

%ConvertToTypeCode
    code
%End

This directive is used to specify the handwritten code that converts a Python object to a mapped type instance. It is used as part of the %MappedType directive and as part of a class specification. The code is also called to determine if the Python object is of the correct type prior to conversion.

When used as part of a class specification is can automatically convert additional types of Python object. For example, PyQt uses it in the specification of the QString class to allow Python string objects and Unicode objects to be used wherever QString instances are expected.

The following variables are made available to the handwritten code:

int *sipIsErr

If this is NULL then the code is being asked to check the type of the Python object. The check must not have any side effects. Otherwise the code is being asked to convert the Python object and a non-zero value should be returned through this pointer if an error occurred during the conversion.

PyObject *sipPy

This is the Python object to be converted.

type **sipCppPtr

This is a pointer through which the address of the mapped type instance (or zero if appropriate) is returned. Its value is undefined if sipIsErr is NULL.

The handwritten code must explicitly return an int that is either zero or non-zero. Its meaning depends on the value of sipIsErr.

If sipIsErr is NULL then a non-zero value is returned if the Python object has a type that can be converted to the mapped type. Otherwise zero is returned.

If sipIsErr is not NULL then a non-zero value is returned if the mapped type instance returned through sipCppPtr was created on the heap. Otherwise zero is returned.

The following example converts a Python list of numbers to a QValueList<int> instance:

%ConvertToTypeCode
    // See if we are just being asked to check the type of the Python
    // object.
    if (sipIsErr == NULL)
        return PyList_Check(sipPy);

    // We map None to a 0 pointer.
    if (sipPy == Py_None)
    {
        *sipCppPtr = 0;

        // There is nothing on the heap.
        return 0;
    }

    // Create the instance on the heap.
    QValueList<int> *qvl = new QValueList<int>;

    PyErr_Clear();

    for (int i = 0; i < PyList_GET_SIZE(sipPy); ++i)
    {
        qvl -> append(PyInt_AsLong(PyList_GET_ITEM(sipPy, i)));

        if (PyErr_Occurred() != NULL)
        {
            // Tidy up.
            delete qvl;

            // Set the error flag.
            *sipIsErr = 1;

            // There is nothing on the heap.
            return 0;
        }
    }

    // Return the instance on the heap.
    *sipCppPtr = qvl;

    // The result is a pointer to an instance on the heap.
    return 1;
%End

6.6   %Copying

%Copying
    text
%End

This directive is used to specify some arbitrary text that will be included at the start of all source files generated by SIP. It is normally used to include copyright and licensing terms.

For example:

%Copying
Copyright (c) 2004 Riverbank Computing Limited
%End

6.7   %Doc

%Doc
    text
%End

This directive is used to specify some arbitrary text that will be extracted by SIP when the -d command line option is used. The directive can be specified any number of times and SIP will concatenate all the separate pieces of text in the order that it sees them.

Documentation that is specified using this directive is local to the module in which it appears. It is ignored by modules that %Import it. Use the %ExportedDoc directive for documentation that should be included by all modules that %Import this one.

For example:

%Doc
<h1>An Example</h1>
<p>
This fragment of documentation is HTML and is local to the module in
which it is defined.
</p>
%End

6.8   %End

This isn't a directive in itself, but is used to terminate a number of directives that allow a block of handwritten code or text to be specified.

6.9   %ExportedDoc

%ExportedDoc
    text
%End

This directive is used to specify some arbitrary text that will be extracted by SIP when the -d command line option is used. The directive can be specified any number of times and SIP will concatenate all the separate pieces of text in the order that it sees them.

Documentation that is specified using this directive will also be included by modules that %Import it.

For example:

%ExportedDoc
==========
An Example
==========

This fragment of documentation is reStructuredText and will appear in the
module in which it is defined and all modules that %Import it.
%End

6.10   %Feature

%Feature name

This directive is used to declare a feature. Features (along with %Platforms and %Timeline) are used by the %If directive to control whether or not parts of a specification are processed or ignored.

Features are mutually independent of each other - any combination of features may be enabled or disable. By default all features are enabled. The SIP -x command line option is used to disable a feature.

If a feature is enabled then SIP will automatically generate a corresponding C preprocessor symbol for use by handwritten code. The symbol is the name of the feature prefixed by SIP_FEATURE_.

For example:

%Feature FOO_SUPPORT

%If (FOO_SUPPORT)
void foo();
%End

6.11   %If

%If (expression)
    specification
%End

where

expression ::= [ored-qualifiers | range]

ored-qualifiers ::= [qualifier | qualifier || ored-qualifiers]

qualifier ::= [!] [feature | platform]

range ::= [version] - [version]

This directive is used in conjunction with features (see %Feature), platforms (see %Platforms) and versions (see %Timeline) to control whether or not parts of a specification are processed or not.

A range of versions means all versions starting with the lower bound up to but excluding the upper bound. If the lower bound is omitted then it is interpreted as being before the earliest version. If the upper bound is omitted then it is interpreted as being after the latest version.

For example:

%Feature SUPPORT_FOO
%Platforms {WIN32_PLATFORM POSIX_PLATFORM MACOS_PLATFORM}
%Timeline {V1_0 V1_1 V2_0 V3_0}

%If (!SUPPORT_FOO)
    // Process this if the SUPPORT_FOO feature is disabled.
%End

%If (POSIX_PLATFORM || MACOS_PLATFORM)
    // Process this if either the POSIX_PLATFORM or MACOS_PLATFORM
    // platforms are enabled.
%End

%If (V1_0 - V2_0)
    // Process this if either V1_0 or V1_1 is enabled.
%End

%If (V2_0 - )
    // Process this if either V2_0 or V3_0 is enabled.
%End

%If ( - )
    // Always process this.
%End

Note that this directive is not implemented as a preprocessor. Only the following parts of a specification are affected by it:

• class
• %ConvertFromTypeCode
• %ConvertToSubClassCode
• %ConvertToTypeCode
• enum
• functions
• %If
• %MappedType
• %MethodCode
• %ModuleCode
• %ModuleHeaderCode
• namespace
• struct
• typedef
• %TypeCode
• %TypeHeaderCode
• variables
• %VirtualCatcherCode

Also note that the only way to specify the logical and of qualifiers is to use nested %If directives.

6.12   %Import

%Import filename

This directive is used to import the specification of another module. This is needed if the current module makes use of any types defined in the imported module, e.g. as an argument to a function, or to sub-class.

If filename cannot be opened then SIP prepends filename with the name of the directory containing the current specification file (i.e. the one containing the %Import directive) and tries again. If this also fails then SIP prepends filename with each of the directories, in turn, specified by the -I command line option.

For example:

%Import qt/qtmod.sip

6.13   %Include

%Include filename

This directive is used to include contents of another file as part of the specification of the current module. It is the equivalent of the C preprocessor's #include directive and is used to structure a large module specification into manageable pieces.

%Include follows the same search process as %Import when trying to open filename.

For example:

%Include qwidget.sip

6.14   %License

%License /license-annotations/

This directive is used to specify the contents of an optional license dictionary. The license dictionary is called __license__ and is stored in the module dictionary. The elements of the dictionary are specified using the Licensee, Signature, Timestamp and Type annotations. Only the Type annotation is compulsory.

Note that this directive isn't an attempt to impose any licensing restrictions on a module. It is simply a method for easily embedding licensing information in a module so that it is accessible to Python scripts.

For example:

%License /Type="GPL"/

6.15   %MappedType

%MappedType type
{
    [header-code]
    [convert-to-code]
    [convert-from-code]
}

This directive is used to define an automatic mapping between a C or C++ type and a Python type. The C/C++ type being mapped must be either a structure, a class, or a template. Mapped types are the only way SIP supports templates.

header-code is the %TypeHeaderCode used to specify the library interface to the type being mapped.

convert-to-code is the %ConvertToTypeCode used to specify the handwritten code that converts a Python object to an instance of the mapped type.

convert-from-code is the %ConvertFromTypeCode used to specify the handwritten code that converts an instance of the mapped type to a Python object.

For example:

%MappedType QValueList<int>
{
%TypeHeaderCode
// Include the library interface to the type being mapped.
#include <qvaluelist.h>
%End

%ConvertToTypeCode
    // See the %ConvertToTypeCode example for the code that converts a
    // Python list of numbers to a QValueList<int> instance.
%End

%ConvertFromTypeCode
    // See the %ConvertFromTypeCode example for the code that converts a
    // QValueList<int> instance to a Python list of numbers.
%End
}

In this example we can use QValueList<int> throughout the module's specification files (and in any module that imports this one). The generated code will automatically map this to and from a Python list of numbers when appropriate.

6.16   %MethodCode

%MethodCode
    code
%End

This directive is used as part of the specification of a global function, class method, operator, constructor or destructor to specify handwritten code that replaces the normally generated call to the function being wrapped. It is usually used to handle argument types and results that SIP cannot deal with automatically.

The specified code is embedded in-line after the function's arguments have been successfully converted from Python objects to their C or C++ equivalents. The specified code must not include any return statements.

The the context of a destructor the specified code is embedded in-line in the Python type's deallocation function.

The specified code must also handle the Python Global Interpreter Lock (GIL). If compatibility with SIP v3.x is required then the GIL must be released immediately before the C++ call and reacquired immediately afterwards as shown in this example fragment:

Py_BEGIN_ALLOW_THREADS
sipCpp -> foo();
Py_END_ALLOW_THREADS

If compatibility with SIP v3.x is not required then this is optional but should be done if the C++ function might block the current thread or take a significant amount of time to execute. (See the ReleaseGIL annotation.)

The following variables are made available to the handwritten code:

type a0

There is a variable for each argument of the Python signature (excluding any self argument) named a0, a1, etc. The type of the variable is the same as the type defined in the specification with the following exceptions:

• if the argument is only used to return a value (e.g. it is an int * without an In annotation) then the type has one less level of indirection (e.g. it will be an int)
• if the argument is a structure or class (or a reference or a pointer to a structure or class) then type will always be a pointer to the structure or class.

Note that handwritten code for destructors never has any arguments.

PyObject *a0Wrapper

This variable is made available only if the corresponding argument wraps a C structure or C++ class instance and the GetWrapper annotation is specified. The variable is a pointer to the Python object that wraps the argument.

type *sipCpp

If the directive is used in the context of a class constructor then this must be set by the handwritten code to the constructed instance. In any other class context then this is a pointer to the class instance. Its type is a pointer to the structure or class.

int sipIsErr

The handwritten code should set this to a non-zero value, and raise an appropriate Python exception, if an error is detected.

sipIsErr is not provided for destructors.

type sipRes

The handwritten code should set this to the result to be returned. The type of the variable is the same as the type defined in the Python signature in the specification with the following exception:

• if the argument is a structure or class (or a reference or a pointer to a structure or class) then type will always be a pointer to the structure or class.

sipRes is not provided for inplace operators (e.g. += or __imul__) as their results are handled automatically, nor for class constructors.

PyObject *sipSelf

If the directive is used in the context of a class method then this is the Python object that wraps the the structure or class instance, i.e. self.

For example:

class Klass
{
public:
    int foo(SIP_PYTUPLE);
%MethodCode
        // The C++ API takes a 2 element array of integers but passing a
        // two element tuple is more Pythonic.

        int iarr[2];

        if (PyArg_ParseTuple(a0, "ii", &iarr[0], &iarr[1]))
        {
            Py_BEGIN_ALLOW_THREADS
            sipRes = sipCpp -> Klass::foo(iarr);
            Py_END_ALLOW_THREADS
        }
        else
        {
            // PyArg_ParseTuple() will have raised the exception.
            sipIsErr = 1;
        }
%End
};

Note the use of the fully scoped method name in the example (i.e. Klass::foo() rather than just foo()). This is required for virtual methods ⁸ in order to avoid virtual call loops, but is a good habit to get into for all public methods.

If a method is in the protected section of a C++ class then the call should instead be:

sipRes = sipCpp -> sipProtect_foo(iarr);

6.17   %Module

%Module name [version]

This directive is used to identify that the library being wrapped is a C++ library and to define the name of the module and it's optional version number.

The optional version number is useful if you (or others) might create other modules that build on this module, i.e. if another module might %Import this module. Under the covers, a module exports an API that is used by modules that %Import it and the API is given a version number. A module built on that module knows the version number of the API that it is expecting. If, when the modules are imported at run-time, the version numbers do not match then a Python exception is raised. The dependent module must then be re-built using the correct specification files for the base module.

The version number should be incremented whenever a module is changed. Some changes don't affect the exported API, but it is good practice to change the version number anyway.

For example:

%Module qt 5

6.18   %ModuleCode

%ModuleCode
    code
%End

This directive is used to specify handwritten code, typically the implementations of utility functions, that can be called by other handwritten code in the module.

For example:

%ModuleCode
// Print an object on stderr for debugging purposes.
void dump_object(PyObject *o)
{
    PyObject_Print(o, stderr, 0);
    fprintf(stderr, "\n");
}
%End

See also %ModuleHeaderCode.

6.19   %ModuleHeaderCode

%ModuleHeaderCode
    code
%End

This directive is used to specify handwritten code, typically the declarations of utility functions, that is placed in a header file that is included by all generated code.

For example:

%ModuleHeaderCode
void dump_object(PyObject *o);
%End

See also %ModuleCode.

6.20   %OptionalInclude

%OptionalInclude filename

This directive is identical to the %Include directive except that SIP silently continues processing if filename could not be opened.

For example:

%OptionalInclude license.sip

6.21   %Platforms

%Platforms {name name ...}

This directive is used to declare a set of platforms. Platforms (along with %Feature and %Timeline) are used by the %If directive to control whether or not parts of a specification are processed or ignored.

Platforms are mutually exclusive - only one platform can be enabled at a time. By default all platforms are disabled. The SIP -t command line option is used to enable a platform.

For example:

%Platforms {WIN32_PLATFORM POSIX_PLATFORM MACOS_PLATFORM}

%If (WIN32_PLATFORM)
void undocumented();
%End

%If (POSIX_PLATFORM)
void documented();
%End

6.22   %PostInitialisationCode

%PostInitialisationCode
    code
%End

This directive is used to specify handwritten code that is embedded in-line at the very end of the generated module initialisation code.

For example:

%PostInitialisationCode
    // The code will be executed when the module is first imported and
    // after all other initialisation has been completed.
%End

6.23   %Timeline

%Timeline {name name ...}

This directive is used to declare a set of versions released over a period of time. Versions (along with %Feature and %Platforms) are used by the %If directive to control whether or not parts of a specification are processed or ignored.

Versions are mutually exclusive - only one version can be enabled at a time. By default all versions are disabled. The SIP -t command line option is used to enable a version.

For example:

%Timeline {V1_0 V1_1 V2_0 V3_0}

%If (V1_0 - V2_0)
void foo();
%End

%If (V2_0 -)
void foo(int = 0);
%End

6.24   %TypeCode

%TypeCode
    code
%End

This directive is used as part of the specification of a C structure or a C++ class to specify handwritten code, typically the implementations of utility functions, that can be called by other handwritten code in the structure or class.

For example:

class Klass
{
%TypeCode
// Print an instance on stderr for debugging purposes.
static void dump_klass(const Klass *k)
{
    fprintf(stderr,"Klass %s at %p\n", k -> name(), k);
}
%End

    // The rest of the class specification.

};

Because the scope of the code is normally within the generated file that implements the type, any utility functions would normally be declared static. However a naming convention should still be adopted to prevent clashes of function names within a module in case the SIP -j command line option is used.

6.25   %TypeHeaderCode

%TypeHeaderCode
    code
%End

This directive is used to specify handwritten code that defines the interface to a C or C++ type being wrapped, either a structure, a class, or a template. It is used within a class definition or a %MappedType directive.

Normally code will be a pre-processor #include statement.

For example:

// Wrap the Klass class.
class Klass
{
%TypeHeaderCode
#include <klass.h>
%End

    // The rest of the class specification.
};

6.26   %VirtualCatcherCode

%VirtualCatcherCode
    code
%End

For most classes there are corresponding generated derived classes that contain reimplementations of the class's virtual methods. These methods (which SIP calls catchers) determine if there is a corresponding Python reimplementation and call it if so. If there is no Python reimplementation then the method in the original class is called instead.

This directive is used to specify handwritten code that replaces the normally generated call to the Python reimplementation and the handling of any returned results. It is usually used to handle argument types and results that SIP cannot deal with automatically.

This directive can also be used in the context of a class destructor to specify handwritten code that is embedded in-line in the internal derived class's destructor.

In the context of a method the Python Global Interpreter Lock (GIL) is automatically acquired before the specified code is executed and automatically released afterwards.

In the context of a destructor the specified code must handle the GIL. The GIL must be acquired before any calls to the Python API and released after the last call as shown in this example fragment:

SIP_BLOCK_THREADS
Py_DECREF(obj);
SIP_UNBLOCK_THREADS

The following variables are made available to the handwritten code in the context of a method:

type a0

There is a variable for each argument of the C++ signature named a0, a1, etc. The type of the variable is the same as the type defined in the specification.

int sipIsErr

The handwritten code should set this to a non-zero value, and raise an appropriate Python exception, if an error is detected.

PyObject *sipMethod

This object is the Python reimplementation of the virtual C++ method. It is normally passed to sipCallMethod().

type sipRes

The handwritten code should set this to the result to be returned. The type of the variable is the same as the type defined in the C++ signature in the specification.

No variables are made available in the context of a destructor.

For example:

class Klass
{
public:
    virtual int foo(SIP_PYTUPLE) [int (int *)];
%MethodCode
        // The C++ API takes a 2 element array of integers but passing a
        // two element tuple is more Pythonic.

        int iarr[2];

        if (PyArg_ParseTuple(a0, "ii", &iarr[0], &iarr[1]))
        {
            Py_BEGIN_ALLOW_THREADS
            sipRes = sipCpp -> Klass::foo(iarr);
            Py_END_ALLOW_THREADS
        }
        else
        {
            // PyArg_ParseTuple() will have raised the exception.
            sipIsErr = 1;
        }
%End
%VirtualCatcherCode
        // Convert the 2 element array of integers to the two element
        // tuple.

        PyObject *result;

        result = sipCallMethod(&sipIsErr, sipMethod, "ii", a0[0], a0[1]);

        if (result != NULL)
        {
            // Convert the result to the C++ type.
            sipParseResult(&sipIsErr, sipMethod, result, "i", &sipRes);

            Py_DECREF(result);
        }
%End
};

7.1   Argument Annotations

// The wrapper for this function will also accept an integer argument
// which Python will automatically convert to a floating point number.
void foo(double);

// The wrapper for this function will never get used.
void foo(int);

// The wrapper for this function will only accept floating point numbers.
void foo(double /Constrained/);

// The wrapper for this function will be used for anything that Python can
// convert to an integer, except for floating point numbers.
void foo(int);

7.2   Class Annotations

7.3   Function Annotations

7.4   License Annotations

8.1   SIP_API_MAJOR_NR

This is a C preprocessor symbol that defines the major number of the SIP API. Its value is a number. There is no direct relationship between this and the SIP version number.

8.2   SIP_API_MINOR_NR

This is a C preprocessor symbol that defines the minor number of the SIP API. Its value is a number. There is no direct relationship between this and the SIP version number.

8.3   SIP_BLOCK_THREADS

This is a C preprocessor macro that will make sure the Python Global Interpreter Lock (GIL) is acquired. Python API calls must only be made when the GIL has been acquired. There must be a corresponding SIP_UNBLOCK_THREADS at the same lexical scope.

8.4   SIP_BUILD

This is a C preprocessor symbol that defines a unique SIP build identifier represented as a string.

8.5   SIP_UNBLOCK_THREADS

This is a C preprocessor macro that will restore the Python Global Interpreter Lock (GIL) to the state it was prior to the corresponding SIP_BLOCK_THREADS.

8.6   SIP_VERSION

This is a C preprocessor symbol that defines the SIP version number represented as a 3 part hexadecimal number (e.g. v4.0.0 is represented as 0x040000).

8.7   SIP_VERSION_STR

This is a C preprocessor symbol that defines the SIP version number represented as a string. For development snapshots it will start with snapshot-.

8.8   sipBadCatcherResult()

void sipBadCatcherResult(PyObject *method)

This is raises a Python exception when the result of a Python reimplementation of a C++ method doesn't have the expected type. It is normally called by handwritten code specified with the %VirtualCatcherCode directive. method is the Python method and would normally be the supplied sipMethod.

8.9   sipBadLengthForSlice()

void sipBadLengthForSlice(int seqlen, int slicelen)

This raises a Python exception when the length of a slice object is inappropriate for a sequence-like object. It is normally called by handwritten code specified for __setitem__() methods. seqlen is the length of the sequence. slicelen is the length of the slice.

8.10   sipBuildResult()

PyObject *sipBuildResult(int *iserr, char *format, ...)

This creates a Python object based on a format string and associated values in a similar way to the Python Py_BuildValue() function. If there was an error then NULL is returned and a Python exception is raised. If iserr is not NULL then the location it points to is set to a non-zero value. format is the string of format characters.

If format begins and ends with parentheses then a tuple of objects is created. If format contains more than one format character then parentheses must be specified.

In the following description the first letter is the format character, the entry in parentheses is the Python object type that the format character will create, and the entry in brackets are the types of the C/C++ values to be passed.

a (string) [char *, int]

Convert a C/C++ character array and its length to a Python string. If the character array is NULL then the length is ignored and the result is Py_None.

b (boolean) [int]

Convert a C/C++ int to a Python boolean.

c (string) [char]

Convert a C/C++ char to a Python string.

d (float) [double]

Convert a C/C++ double to a Python floating point number.

e (integer) [enum]

Convert a C/C++ enum to a Python integer.

f (float) [float]

Convert a C/C++ float to a Python floating point number.

h (integer) [short]

Convert a C/C++ short to a Python integer.

i (integer) [int]

Convert a C/C++ int to a Python integer.

l (integer) [long]

Convert a C/C++ long to a Python integer.

s (string) [char *]

Convert a C/C++ '\0' terminated string to a Python string. If the string pointer is NULL then the result is Py_None.

M (wrapped instance) [type *, sipWrapperType *]

Convert a C structure or a C++ class instance to a Python class instance object. If the structure or class instance has already been wrapped then the result is a new reference to the existing class instance object. The Python class is influenced by any applicable %ConvertToSubClassCode code.

N (wrapped instance) [type *, sipWrapperType *]

Convert a C structure or a C++ class instance to a Python class instance object. This should not be used if the structure or class instance might already have been wrapped. The Python class is influenced by any applicable %ConvertToSubClassCode code. It is recommended that handwritten code use the M format character instead.

O (wrapped instance) [type *, sipWrapperType *]

Convert a C structure or a C++ class instance to a Python class instance object. If the structure or class instance has already been wrapped then the result is a new reference to the existing class instance object. It is recommended that handwritten code use the M format character instead.

P (wrapped instance) [type *, sipWrapperType *]

Convert a C structure or a C++ class instance to a Python class instance object. This should not be used if the structure or class instance might already have been wrapped. It is recommended that handwritten code use the M format character instead.

R (object) [PyObject *]

The result is value passed without any conversions. The reference count is unaffected, i.e. a reference is taken.

S (object) [PyObject *]

The result is value passed without any conversions. The reference count is incremented.

T (object) [void *, PyObject *(*)(void *cppptr)]

Convert a C structure or a C++ class instance to a Python object using a convertor function. See Generated Type Convertors.

V (sip.voidptr) [void *]

Convert a C/C++ void * Python sip.voidptr object.

8.11   sipCallMethod()

PyObject *sipCallMethod(int *iserr, PyObject *method, char *format, ...)

This calls a Python method passing a tuple of arguments based on a format string and associated values in a similar way to the Python PyObject_CallObject() function. If there was an error then NULL is returned and a Python exception is raised. If iserr is not NULL then the location it points to is set to a non-zero value. method is the Python bound method to call. format is the string of format characters (see sipBuildResult()).

This is normally called by handwritten code specified with the %VirtualCatcherCode directive with method being the supplied sipMethod.

8.12   sipClassName()

PyObject *sipClassName(PyObject *obj)

This returns the class name of a wrapped instance as a Python string. It comes with a reference.

8.13   sipConnectRx()

PyObject *sipConnectRx(PyObject *sender, const char *signal, PyObject *receiver, const char *slot)

This connects a signal to a signal or slot and returns Py_True if the signal was connected or Py_False if not. If there was some other error then a Python exception is raised and NULL is returned. sender is the wrapped QObject derived instance that emits the signal. signal is the typed name of the signal. receiver is the wrapped QObject derived instance or Python callable that the signal is connected to. slot is the typed name of the slot, or NULL if receiver is a Python callable. It is normally only used by PyQt to implement QObject.connect().

This is only available if Qt support is enabled.

8.14   sipConvertFromSequenceIndex()

int sipConvertFromSequenceIndex(int idx, int len)

This converts a Python sequence index (i.e. where a negative value refers to the offset from the end of the sequence) to a C/C++ array index. If the index was out of range then a negative value is returned and a Python exception raised.

8.15   sipConvertFromSliceObject()

int sipConvertFromSliceObject(PyObject *slice, int length, int *start, int *stop, int *step, int *slicelength)

This is a thin wrapper around the Python PySlice_GetIndicesEx() function provided to make it easier to write handwritten code that is compatible with SIP v3.x and versions of Python earlier that v2.3.

8.16   sipConvertToCpp()

void *sipConvertToCpp(PyObject *obj, sipWrapperType *type, int *iserr)

This extracts the pointer to the C structure or C++ class instance from a wrapped instance object. obj is the wrapped instance object (if it is Py_None then NULL is returned). type is generated type corresponding to the C/C++ type returned. It may be any class in the object's class hierarchy. If there is an error then the location iserr points to is set to a non-zero value.

8.17   sipDisconnectRx()

PyObject *sipDisconnectRx(PyObject *sender, const char *signal, PyObject *receiver, const char *slot)

This disconnects a signal from a signal or slot and returns Py_True if the signal was disconnected or Py_False if not. If there was some other error then a Python exception is raised and NULL is returned. sender is the wrapped QObject derived instance that emits the signal. signal is the typed name of the signal. receiver is the wrapped QObject derived instance or Python callable that the signal is connected to. slot is the typed name of the slot, or NULL if receiver is a Python callable. It is normally only used by PyQt to implement QObject.disconnect().

This is only available if Qt support is enabled.

8.18   sipEmitSignal()

int sipEmitSignal(PyObject *txobj, const char *signal, PyObject *args)

This emits a signal and returns zero if there was no error. If there was an error then a Python exception is raised and a negative value is returned. txobj is the wrapped QObject derived instance that emits the signal. signal is the typed name of the signal. args is a Python tuple of the signal arguments. It is normally only used by PyQt to implement QObject.emit().

This is only available if Qt support is enabled.

8.19   sipFree()

void sipFree(void *mem)

This returns an area of memory allocated by sipMalloc() to the heap. mem is a pointer to the area of memory.

8.20   sipGetSender()

void *sipGetSender()

This returns a pointer to the last QObject instance that emitted a Qt signal. It is normally only used by PyQt to implement QObject.sender().

This is only available if Qt support is enabled.

8.21   sipGetWrapper()

PyObject *sipGetWrapper(void *cppptr, sipWrapperType *type)

This returns a borrowed reference to the wrapped instance object for a C structure or C++ class instance. If the structure or class instance hasn't been wrapped then NULL is returned (and no Python exception is raised). cppptr is the pointer to the structure or class instance. type is the generated type corresponding to the C/C++ type.

8.22   sipIntTypeClassMap

This C structure is used with sipMapIntToClass() to define a mapping between integer based RTTI and generated type objects. The structure elements are as follows.

int typeInt

The integer RTTI.

sipWrapperType **pyType.

A pointer to the corresponding Python type object.

8.23   sipIsSubClassInstance()

int sipIsSubClassInstance(PyObject *obj, sipWrapperType *type)

This is a thin wrapper around the Python PyObject_TypeCheck() function provided to make it easier to write handwritten code that is compatible with SIP v3.x and versions of Python earlier that v2.2.

8.24   sipMalloc()

void *sipMalloc(size_t nbytes)

This allocates an area of memory of size nytes on the heap using the Python PyMem_Malloc() function. If there was an error then NULL is returned and a Python exception raised. See sipFree().

8.25   sipMapIntToClass()

sipWrapperType *sipMapIntToClass(int type, const sipIntTypeClassMap *map, int maplen)

This is used in %ConvertToSubClassCode code as a convenient way of converting integer based RTTI to the corresponding Python type object. type is the RTTI. map is the table of known RTTI and the corresponding type objects (see sipIntTypeClassMap). The entries in the table must be sorted in ascending order of RTTI. maplen is the number of entries in the table. The corresponding Python type object is returned, or NULL if type wasn't in map.

8.26   sipMapStringToClass()

sipWrapperType *sipMapStringToClass(char *type, const sipStringTypeClassMap *map, int maplen)

This is used in %ConvertToSubClassCode code as a convenient way of converting '\0' terminated string based RTTI to the corresponding Python type object. type is the RTTI. map is the table of known RTTI and the corresponding type objects (see sipStringTypeClassMap). The entries in the table must be sorted in ascending order of RTTI. maplen is the number of entries in the table. The corresponding Python type object is returned, or NULL if type wasn't in map.

8.27   sipParseResult()

int sipParseResult(int *iserr, PyObject *method, PyObject *result, char *format, ...)

This converts a Python object (usually returned by a method) to C/C++ based on a format string and associated values in a similar way to the Python PyArg_ParseTuple() function. If there was an error then a negative value is returned and a Python exception is raised. If iserr is not NULL then the location it points to is set to a non-zero value. method is the Python bound method that returned the result object. format is the string of format characters.

This is normally called by handwritten code specified with the %VirtualCatcherCode directive with method being the supplied sipMethod and result being the value returned by sipCallMethod().

If format begins and ends with parentheses then result must be a Python tuple and the rest of format is applied to the tuple contents.

In the following description the first letter is the format character, the entry in parentheses is the Python object type that the format character will convert, and the entry in brackets are the types of the C/C++ values to be passed.

a (string) [char **, int *]

Convert a Python string to a C/C++ character array and its length. If the Python object is Py_None then the array and length are NULL and zero respectively.

b (integer) [bool *]

Convert a Python integer to a C/C++ bool.

c (string) [char *]

Convert a Python string of length 1 to a C/C++ char.

d (float) [double *]

Convert a Python floating point number to a C/C++ double.

e (integer) [enum *]

Convert Python integer to a C/C++ enum.

f (float) [double *]

Convert a Python floating point number to a C/C++ float.

h (integer) [short *]

Convert a Python integer to a C/C++ short.

i (integer) [int *]

Convert a Python integer to a C/C++ int.

l (integer) [long *]

Convert a Python integer to a C/C++ long.

s (string) [char **]

Convert a Python string to a C/C++ '\0' terminated string. If the Python object is Py_None then the string is NULL.

L (object) [type *(*)(PyObject *obj, int *iserr), void **]

Convert a Python object to a C structure or a C++ class instance using a convertor function. See Generated Type Convertors.

M (object) [type *(*)(PyObject *obj, int *iserr), void **]

Convert a Python object to a C structure or a C++ class instance using a convertor function. If the structure or class instance pointer is NULL then return an error. See Generated Type Convertors.

N (object) [PyTypeObject *, PyObject **]

A Python object is checked to see if it is a certain type and then returned without any conversions. The reference count is incremented. The Python object may be Py_None.

O (object) [PyObject **]

A Python object is returned without any conversions. The reference count is incremented.

T (object) [PyTypeObject *, PyObject **]

A Python object is checked to see if it is a certain type and then returned without any conversions. The reference count is incremented. The Python object may not be Py_None.

V (sip.voidptr) [void *]

Convert a Python sip.voidptr object to a C/C++ void *.

Z (object) []

Check that a Python object is Py_None. No value is returned.

8.28   sipStringTypeClassMap

This C structure is used with sipMapStringToClass() to define a mapping between '\0' terminated string based RTTI and generated type objects. The structure elements are as follows.

char *typeString

The '\0' terminated string RTTI.

sipWrapperType **pyType.

A pointer to the corresponding Python type object.

8.29   sipTransfer()

void sipTransfer(PyObject *obj, int tocpp)

This transfers ownership of a Python wrapped instance either to or from Python (see Ownership of Objects). obj is the wrapped instance. If tocpp is non-zero then ownership is transfered from Python to C/C++. If tocpp is zero then ownership is transfered from C/C++ to Python.

8.30   sipWrapperType

This is a C structure that represents a SIP generated type object. It is an extension of the Python PyTypeObject structure (which is itself an extension of the Python PyObject structure) and so may be safely cast to PyTypeObject (and PyObject).

8.31   Generated Type Convertors

SIP generates functions for all types being wrapped (including mapped types defined with the %MappedType directive) that convert a Python object to the C structure or C++ class instance. The name of this convertor is the name of the structure or class prefixed by sipForceConvertTo_.

void *sipForceConvertTo_*class*(PyObject *obj, int *iserr)

obj is the Python object to convert. If obj is NULL or the location pointed to by iserr is non-zero then the conversion is not attempted and NULL is returned. If there was an error then the location pointed to by iserr is set to a non-zero value, a Python exception is raised, and NULL is returned.

SIP also generates functions for mapped types that convert a C structure or C++ class instance to a Python object. The name of this convertor is the name of the structure or class prefixed by sipConvertFrom_.

PyObject *sipConvertFrom_*class*(void *cppptr)

cppptr is a pointer to the C structure or C++ class instance to convert. If there was an error then NULL is returned and a Python exception raised.

The convertor functions of all imported types are available to handwritten code.

8.32   Generated Type Objects

SIP generates a type object for each C structure or C++ class being wrapped. These are sipWrapperType structures and are used extensively by the SIP API.

These objects are named with the structure or class name prefixed by sipClass_. For example, the type object for class Klass is sipClass_Klass.

The type objects of all imported classes are available to handwritten code.

8.33   Generated Derived Classes

For most C++ classes being wrapped SIP generates a derived class with the same name prefixed by sip. For example, the derived class for class Klass is sipKlass.

If a C++ class doesn't have any virtual or protected methods in it or any of it's super-class hierarchy, or does not emit any Qt signals, then a derived class is not generated.

Most of the time handwritten code should ignore the derived classes. The only exception is that handwritten constructor code specified using the %MethodCode directive should call the derived class's constructor (which has the same C++ signature) rather then the wrapped class's constructor.

10.1   sipconfig Functions

create_config_module(module, template, content)

This creates a configuration module (e.g. pyqtconfig) from a template file and a string.

module is the name of the configuration module file to create.

template is the name of the template file.

content is a string which replaces every occurence of the pattern @SIP_CONFIGURATION@ in the template file. The content string is usually created from a Python dictionary using sipconfig.create_content().

create_content(dict, dictname="_pkg_config")

This converts a Python dictionary to a string that can be parsed by the Python interpreter and converted back to an equivalent dictionary. It is typically used to generate the content string for sipconfig.create_config_module().

dict is the Python dictionary to convert.

dictname is the optional name of the dictionary.

Returns the dictionary as a string.

error(msg)

This displays an error message on stderr and calls sys.exit() with a value of 1.

msg is the text of the message and should not include any newline characters.

format(msg, leftmargin=0, rightmargin=78)

This formats a message by inserting newline characters at appropriate places.

msg is the text of the message and should not include any newline characters.

leftmargin is the optional position of the left margin.

rightmargin is the optional position of the right margin.

inform(msg)

This displays an information message on stdout.

msg is the text of the message and should not include any newline characters.

read_version(filename, description, numdefine=None, strdefine=None)

This extracts version information for a package from a file, usually a C or C++ header file. The version information must each be specified as a #define of a numeric (hexadecimal or decimal) value and/or a string value.

filename is the name of the file to read.

description is a descriptive name of the package used in error messages.

numdefine is the optional name of the #define of the version as a number. If it is None then the numeric version is ignored.

strdefine is the optional name of the #define of the version as a string. If it is None then the string version is ignored.

Returns a tuple of the numeric and string versions. sipconfig.error() is called if either were required but could not be found.

version_to_sip_tag(version, tags, description)

This converts a version number to a SIP version tag. SIP uses the %Timeline directive to define the chronology of the different versions of the C/C++ library being wrapped. Typically it is not necessary to define a version tag for every version of the library, but only for those versions that affect the library's API as SIP sees it.

version is the numeric version number of the C/C++ library being wrapped. If it is negative then the latest version is assumed. (This is typically useful if a snapshot is indicated by a negative version number.)

tags is the dictionary of SIP version tags keyed by the corresponding C/C++ library version number. The tag used is the one with the smallest key (i.e. earliest version) that is greater than version.

description is a descriptive name of the C/C++ library used in error messages.

Returns the SIP version tag. sipconfig.error() is called if the C/C++ library version number did not correspond to a SIP version tag.

version_to_string(v)

This converts a 3 part version number encoded as a hexadecimal value to a string.

v is the version number.

Returns a string.

10.2   sipconfig Classes

Configuration

This class encapsulates configuration values that can be accessed as instance objects. A sub-class may provide a dictionary of additional configuration values in its constructor the elements of which will have precedence over the super-class's values.

The following configuration values are provided:

default_bin_dir

The name of the directory where executables should be installed by default.

default_mod_dir

The name of the directory where SIP generated modules should be installed by default.

default_sip_dir

The name of the base directory where the .sip files for SIP generated modules should be installed by default. A sub-directory with the same name as the module should be created and its .sip files should be installed in the sub-directory. The .sip files only need to be installed if you might want to build other bindings based on them.

py_inc_dir

The name of the directory containing the Python.h header file.

py_lib_dir

The name of the directory containing the Python interpreter library.

py_version

The Python version as a 3 part hexadecimal number (e.g. v2.3.3 is represented as 0x020303).

qt_dir

The name of the Qt base directory. The value is not present if Qt support is disabled.

qt_edition

The name of the Qt edition (e.g. enterprise, professional, free). The value is not present if Qt support is disabled.

qt_inc_dir

The name of the Qt include directory. The value is not present if Qt support is disabled.

qt_lib

The name of the Qt library with platform dependent prefixes, suffixes and version numbers removed (e.g. qt, qt-mt). The value is not present if Qt support is disabled.

qt_lib_dir

The name of the Qt library directory. The value is not present if Qt support is disabled.

qt_threaded

A non-zero value if the Qt library includes support for threads. The value is not present if Qt support is disabled.

qt_version

The Qt version as a 3 part hexadecimal number (e.g. v3.3.0 is represented as 0x030300). It is 0 if Qt support is disabled.

qt_winconfig

A string describing the Qt configuration under Windows. The value is not present if Qt support is disabled.

sip_bin

The full pathname of the SIP executable.

sip_inc_dir

The name of the directory containing the sip.h header file.

sip_mod_dir

The name of the directory containing the SIP module.

sip_version

The SIP version as a 3 part hexadecimal number (e.g. v4.0.0 is represented as 0x040000).

sip_version_str

The SIP version as a string. For development snapshots it will start with snapshot-.

__init__(self, sub_cfg=None)

Initialise the instance.

sub_cfg is an optional list of sub-class configurations. It should only be used by the __init__() method of a sub-class to append its own dictionary of configuration values before passing the list to its super-class.

Makefile

This class encapsulates a Makefile. It is intended to be sub-classed to generate Makefiles for particular purposes. It handles all platform and compiler specific flags, but allows them to be adjusted to suit the requirements of a particular module or program. These are defined using a number of macros which can be accessed as instance objects.

The following instance objects are provided to help in fine tuning the generated Makefile:

chkdir

A string that will check for the existence of a directory.

config

A reference to the configuration argument that was passed to the constructor.

console

A reference to the console argument that was passed to the constructor.

copy

A string that will copy a file.

extra_cflags

A list of additional flags passed to the C compiler.

extra_cxxflags

A list of additional flags passed to the C++ compiler.

extra_defines

A list of additional macro names passed to the C/C++ preprocessor.

extra_include_dirs

A list of additional include directories passed to the C/C++ preprocessor.

extra_lflags

A list of additional flags passed to the linker.

extra_lib_dirs

A list of additional library directories passed to the linker.

extra_libs

A list of additional libraries passed to the linker. The names of the libraries must be in platform neutral form (i.e. without any platform specific prefixes, version numbers or extensions).

generator

A string that defines the platform specific style of Makefile. The only supported values are UNIX and something else that is not UNIX.

mkdir

A string that will create a directory.

rm

A string that will remove a file.

__init__(self, configuration, console=0, qt=0, opengl=0, python=0, threaded=0, warnings=None, debug=0, dir=None, makefile="Makefile", installs=None)

Initialise the instance.

configuration is the current configuration and is an instance of the Configuration class or a sub-class.

console is set if the target is a console (rather than GUI) target. This only affects Windows and is ignored on other platforms.

qt is set if the target uses Qt.

opengl is set if the target uses OpenGL.

python is set if the target uses Python.h.

threaded is set if the target requires thread support. It is set automatically if the target uses Qt and Qt has thread support enabled.

warnings is set if compiler warning messages should be enabled. The default of None means that warnings are enabled for SIP v4.x and disabled for SIP v3.x.

debug is set if debugging symbols should be generated.

dir is the name of the directory where build files are read from and Makefiles are written to. The default of None means the current directory is used.

makefile is the name of the generated Makefile.

installs is a list of extra install targets. Each element is a two part list, the first of which is the source and the second is the destination. If the source is another list then it is a list of source files and the destination is a directory.

clean_build_file_objects(self, mfile, build)

This generates the Makefile commands that will remove any files generated during the build of the default target.

mfile is the Python file object of the Makefile.

build is the dictionary created from parsing the build file.

finalise(self)

This is called just before the Makefile is generated to ensure that it is fully configured. It must be reimplemented by a sub-class.

generate(self)

This generates the Makefile.

generate_macros_and_rules(self, mfile)

This is the default implementation of the Makefile macros and rules generation.

mfile is the Python file object of the Makefile.

generate_target_clean(self, mfile)

This is the default implementation of the Makefile clean target generation.

mfile is the Python file object of the Makefile.

generate_target_default(self, mfile)

This is the default implementation of the Makefile default target generation.

mfile is the Python file object of the Makefile.

generate_target_install(self, mfile)

This is the default implementation of the Makefile install target generation.

mfile is the Python file object of the Makefile.

install_file(self, mfile, src, dst)

This generates the Makefile commands to install one or more files to a directory.

mfile is the Python file object of the Makefile.

src is the name of a single file to install or a list of a number of files to install.

dst is the name of the destination directory.

optional_list(self, name)

This returns an optional Makefile macro as a list.

name is the name of the macro.

Returns the macro as a list.

optional_string(self, name, default="")

This returns an optional Makefile macro as a string.

name is the name of the macro.

default is the optional default value of the macro.

Returns the macro as a string.

parse_build_file(self, filename)

This parses a build file (created with the -b SIP command line option).

filename is the name of the build file.

Returns a dictionary corresponding to the parsed build file.

platform_lib(self, clib)

This converts a library name to a platform specific form.

clib is the name of the library in cannonical form.

Return the platform specific name.

ready(self)

This is called to ensure that the Makefile is fully configured. It is normally called automatically when needed.

required_string(self, name)

This returns a required Makefile macro as a string.

name is the name of the macro.

Returns the macro as a string. An exception is raised if the macro does not exist or has an empty value.

ModuleMakefile(Makefile)

This class encapsulates a Makefile to build a generic Python extension module.

__init__(self, configuration, build_file, install_dir=None, static=0, console=0, opengl=0, threaded=0, warnings=None, debug=0, dir=None, makefile="Makefile", installs=None)

Initialise the instance.

configuration - see sipconfig.Makefile.__init__().

build_file is the name of the build file. Build files are generated using the -b SIP command line option.

install_dir is the name of the directory where the module will be optionally installed.

static is set if the module should be built as a static library.

console - see sipconfig.Makefile.__init__().

qt - see sipconfig.Makefile.__init__().

opengl - see sipconfig.Makefile.__init__().

threaded - see sipconfig.Makefile.__init__().

warnings - see sipconfig.Makefile.__init__().

debug - see sipconfig.Makefile.__init__().

dir - see sipconfig.Makefile.__init__().

makefile - see sipconfig.Makefile.__init__().

installs - see sipconfig.Makefile.__init__().

finalise(self)

This is a reimplementation of sipconfig.Makefile.finalise().

generate_macros_and_rules(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_macros_and_rules().

generate_target_clean(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_clean().

generate_target_default(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_default().

generate_target_install(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_install().

module_as_lib(self, mname)

This returns the name of a SIP v3.x module for when it is used as a library to be linked against. An exception will be raised if it is used with SIP v4.x modules.

mname is the name of the module.

Returns the corresponding library name.

ParentMakefile(Makefile)

This class encapsulates a Makefile that sits above a number of other Makefiles in sub-directories.

__init__(self, configuration, subdirs, dir=None, makefile="Makefile", installs=None)

Initialise the instance.

configuration - see sipconfig.Makefile.__init__().

subdirs is the sequence of sub-directories.

dir - see sipconfig.Makefile.__init__().

makefile - see sipconfig.Makefile.__init__().

installs - see sipconfig.Makefile.__init__().

generate_macros_and_rules(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_macros_and_rules().

generate_target_clean(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_clean().

generate_target_default(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_default().

generate_target_install(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_install().

ProgramMakefile(Makefile)

This class encapsulates a Makefile to build an executable program.

__init__(self, configuration, build_file=None, install_dir=None, console=0, qt=0, opengl=0, python=0, threaded=0, warnings=None, debug=0, dir=None, makefile="Makefile", installs=None)

Initialise the instance.

configuration - see sipconfig.Makefile.__init__().

build_file is the name of the optional build file. Build files are generated using the -b SIP command line option.

install_dir is the name of the directory where the executable program will be optionally installed.

console - see sipconfig.Makefile.__init__().

qt - see sipconfig.Makefile.__init__().

opengl - see sipconfig.Makefile.__init__().

python - see sipconfig.Makefile.__init__().

threaded - see sipconfig.Makefile.__init__().

warnings - see sipconfig.Makefile.__init__().

debug - see sipconfig.Makefile.__init__().

dir - see sipconfig.Makefile.__init__().

makefile - see sipconfig.Makefile.__init__().

installs - see sipconfig.Makefile.__init__().

build_command(self, source)

This creates a single command line that will create an executable program from a single source file.

source is the name of the source file.

Returns a tuple of the name of the executable that will be created and the command line.

finalise(self)

This is a reimplementation of sipconfig.Makefile.finalise().

generate_macros_and_rules(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_macros_and_rules().

generate_target_clean(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_clean().

generate_target_default(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_default().

generate_target_install(self, mfile)

This is a reimplementation of sipconfig.Makefile.generate_target_install().

SIPModuleMakefile(ModuleMakefile)

This class encapsulates a Makefile to build a SIP generated Python extension module.

finalise(self)

This is a reimplementation of sipconfig.Makefile.finalise().