Guidelines

This page is intended as a guide describing the process of writing a language binding for the GObject Introspection framework.

  • Decide if you want to make a language binding which is implementation agnostic or implementation specific. Some languages such as Python have libraries which are available across implementations. The Python module ctypes is a binding for the libffi language binding, which is implemented in a couple of different Python implementations. It’s usually easier to target a specific interpreter or compiler implementation so if you unsure, write a specific one.

  • For interpreted language implementations, construct the language binding on top of the libgirepository library instead of writing a code generator. It’ll make it easier for developers to use your language binding as they will be able to read the typelibs in runtime without having an extra intermediate step to generate the language specific metadata. The libgirepository library can also be used for bindings based upon code generators as an optimization, its a lot faster to read metadata from the typelib than it is to extract the metadata from the GIR XML files.

  • Use the Everything library in your unittests, aim at testing all functions there. Do testing as early as possible in the development of the binding, as the code is likely to be more complex than you anticipate.

  • Use the same coding style as your language. If libraries for your language normally uses underscores do that as well. For instance, Java bindings should have a method on it’s GtkButton wrapper called setLabel and not set_label.

  • If there are existing GObject bindings, reuse them for improved compatibility. It’s a nice feature being able to use static bindings and introspected bindings together. The Perl & Python bindings does that.

  • Try to stay close to the C language semantics, for instance GObject should be mapped to a class and gtk_button_set_label to a method of that class:

    • java: button.setLabel("foo")
    • javascript/python/vala: button.set_label("foo")
    • perl: $button->set_label("foo")
    • scheme: (send button (set-label "foo"))