GObject introspection is a middleware layer between C GObject libraries and language bindings. The C library is scanned at compile time to generate a metadata file. At runtime, language bindings can read this metadata and automatically provide bindings to call into the native C library.
GObject introspection is a middleware layer between C libraries (which must use gobject) and language bindings. The C library can be scanned at compile time and generate a metadata file, in addition to the actual native C library. Then at runtime, language bindings can read this metadata and automatically provide bindings to call into the C library.
Two-level applications: C and your favorite runtime.
It makes sense to build many kinds of applications using (at least) two different levels and languages. Those being C + GObject, and a managed (garbage-collection) runtime. C is good for graphics, multimedia, and lower level systems. However, writing complex software is difficult and error-prone without garbage collection. A managed runtime such as Vala, JavaScript, Python, Java, Lua, .NET, Scheme etc. makes a lot of sense for non-fast-path application logic such as configuration, layout and dialogs.
Thus, one of the major goals of the GObject introspection project is to be a convenient bridge between these two worlds, and allow you to choose the right tool for the job, rather than being limited inside one or the other. With the introspection project, you can write for example a ClutterActor or GtkWidget subclass in C, and then without any additional work use that class in JavaScript.
