pyModule.h

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//
// Copyright 2016 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifdef PXR_BASE_TF_PY_MODULE_H
#error This file should only be included once in any given source (.cpp) file.
#endif
#define PXR_BASE_TF_PY_MODULE_H

#include "pxr/pxr.h"

#include "pxr/base/arch/attributes.h"
#include "pxr/base/tf/api.h"
#include "pxr/base/tf/preprocessorUtilsLite.h"

#include "pxr/external/boost/python/module.hpp"

// Helper macros for module files.  If you implement your wrappers for classes
// as functions named wrapClassName(), then you can create your module like
// this:
//
// TF_WRAP_MODULE(ModuleName) {
//    TF_WRAP(ClassName1);
//    TF_WRAP(ClassName2);
//    TF_WRAP(ClassName3);
// }
//

// Forward declare the function that will be provided that does the wrapping.
static void WrapModule();

PXR_NAMESPACE_OPEN_SCOPE

TF_API
void Tf_PyInitWrapModule(void (*wrapModule)(),
                         const char* packageModule,
                         const char* packageName,
                         const char* packageTag,
                         const char* packageTag2);

ARCH_EXPORT
void TF_PP_CAT(init_module_, MFB_PACKAGE_NAME)() {

    Tf_PyInitWrapModule(
        WrapModule,
        TF_PP_STRINGIZE(MFB_PACKAGE_MODULE),
        TF_PP_STRINGIZE(MFB_ALT_PACKAGE_NAME),
        "Wrap " TF_PP_STRINGIZE(MFB_ALT_PACKAGE_NAME),
        TF_PP_STRINGIZE(MFB_PACKAGE_NAME)
        );
}

PXR_NAMESPACE_CLOSE_SCOPE

// When we generate boost python bindings for a library named Foo, 
// we generate a python package that has __init__.py and _Foo.so, 
// and we put all the python bindings in _Foo.so.  The __init__.py 
// file imports _Foo and then publishes _Foo's symbols as its own.  
// Since the module with the bindings is named _Foo, the PyInit routine 
// must be named PyInit_Foo.  This little block produces that function.
//
// See https://docs.python.org/3/c-api/module.html#initializing-c-modules_
//
extern "C"
ARCH_EXPORT
PyObject* TF_PP_CAT(PyInit__, MFB_PACKAGE_NAME)() {

    static struct PyModuleDef moduledef = {
        PyModuleDef_HEAD_INIT,
        TF_PP_STRINGIZE(TF_PP_CAT(_, MFB_PACKAGE_NAME)),    // m_name
        0,                                                  // m_doc
        -1,                                                 // m_size
        NULL,                                               // m_methods
        0,                                                  // m_reload
        0,                                                  // m_traverse
        0,                                                  // m_clear
        0,                                                  // m_free
    };

    PXR_NAMESPACE_USING_DIRECTIVE
    return pxr_boost::python::detail::init_module(moduledef,
                TF_PP_CAT(init_module_, MFB_PACKAGE_NAME));
}

// We also support the case where both the library contents and the 
// python bindings go into libfoo.so.  We still generate a package named foo
// but the __init__.py file in the package foo imports libfoo and
// publishes it's symbols as its own.  Since the module with the
// bindings is named libfoo, the init routine must be named PyInit_libfoo.
// This little block produces that function.
//
// So there are two init routines in every library, but only the one
// that matches the name of the python module will be called by python
// when the module is imported.  So the total cost is a 1-line
// function that doesn't get called.
//
extern "C"
ARCH_EXPORT
PyObject* TF_PP_CAT(PyInit_lib, MFB_PACKAGE_NAME)() {

    static struct PyModuleDef moduledef = {
        PyModuleDef_HEAD_INIT,
        TF_PP_STRINGIZE(TF_PP_CAT(lib, MFB_PACKAGE_NAME)),    // m_name
        0,                                                    // m_doc
        -1,                                                   // m_size
        NULL,                                                 // m_methods
        0,                                                    // m_reload
        0,                                                    // m_traverse
        0,                                                    // m_clear
        0,                                                    // m_free
    };

    PXR_NAMESPACE_USING_DIRECTIVE
    return pxr_boost::python::detail::init_module(moduledef, 
                TF_PP_CAT(init_module_, MFB_PACKAGE_NAME));
}


#define TF_WRAP_MODULE static void WrapModule()

// Declares and calls the class wrapper for x
#define TF_WRAP(x) ARCH_HIDDEN void wrap ## x (); wrap ## x ()