Generating the .defs files.

Generating the .defs files.
	Appendix G. Wrapping C Libraries with gmmproc

The .defs file are text files, in a lisp format, that describe the API of a C library, including its

objects (GObjects, widgets, interfaces, boxed-types and plain structs)
functions
enums
signals
properties
vfuncs

At the moment, we have separate tools for generating different parts of these .defs, so we split them up into separate files. For instance, in the gtk/src directory of the gtkmm sources, you will find these files:

gtk.defs: Includes the other files.
gtk_methods.defs: Objects and functions.
gtk_enums.defs: Enumerations.
gtk_signals.defs: Signals and properties.
gtk_vfuncs.defs: vfuncs (function pointer member fields in structs), written by hand.

Generating the methods .defs

This .defs file describes objects and their functions. It is generated by the h2def.py script which you can find in pygobject's codegen directory. For instance,

$ ./h2def.py /usr/include/gtk-2.0/gtk/*.h > gtk_methods.defs

Generating the enums .defs

This .defs file describes enum types and their possible values. It is generated by the enum.pl script which you can find in glibmm's tools directory. For instance,

$ ./enum.pl /usr/include/gtk-2.0/gtk/*.h > gtk_enums.defs

Generating the signals and properties .defs

This .defs file describes signals and properties. It is generated by the special extra_defs utility that is in every wrapping project, such as gtkmm/tools/extra_defs_gen/. For instance

$ cd tools/extra_defs_gen
$ ./generate_extra_defs > gtk_signals.defs

You must edit the source code of your own generate_extra_defs tool in order to generate the .defs for the GObject C types that you wish to wrap. In the skeleton source tree, the source file is named codegen/extradefs/generate_extra_defs_skeleton.cc. If not done so already, the file should be renamed, with the basename of your new binding substituted for the skeleton placeholder. The codegen/Makefile.am file should also mention the new source filename.

Then edit the .cc file to specify the correct types. For instance, your main() function might look like this:

#include <libsomething.h>

int main(int, char**)
{
  something_init();

  std::cout << get_defs(EXAMPLE_TYPE_SOMETHING)
            << get_defs(EXAMPLE_TYPE_THING);
  return 0;
}


Appendix G. Wrapping C Libraries with gmmproc		The .hg and .ccg files