# Related Tools

Several useful developer tools have been build around GObject technology. The next sections briefly introduce them and link to the respective project pages.

For example, writing GObjects is often seen as a tedious task. It requires a lot of typing and just doing a copy/paste requires a great deal of care. A lot of projects and scripts have been written to generate GObject skeleton form boilerplate code, or even translating higher-level language into plain C.

## Vala

From the Vala homepage itself: Vala is a new programming language that aims to bring modern programming language features to GNOME developers without imposing any additional runtime requirements and without using a different ABI compared to applications and libraries written in C.

The syntax of Vala is similar to C#. The available compiler translates Vala into GObject C code. It can also compile non-GObject C, using plain C API.

## GObject builder

In order to help a GObject class developper, one obvious idea is to use some sort of templates for the skeletons. and then run them through a special tool to generate the real C files. GOB (or GOB2) is such a tool. It is a preprocessor which can be used to build GObjects with inline C code so that there is no need to edit the generated C code. The syntax is inspired by Java and Yacc or Lex. The implementation is intentionally kept simple: the inline C code provided by the user is not parsed.

## Graphical inspection of GObjects

Yet another tool that you may find helpful when working with GObjects is G-Inspector. It is able to display GLib/GTK+ objects and their properties.

## Debugging reference count problems

The reference counting scheme used by GObject does solve quite a few memory management problems but also introduces new sources of bugs. In large applications, finding the exact spot where the reference count of an Object is not properly handled can be very difficult. Hopefully, there exist a tool named refdbg which can be used to automate the task of tracking down the location of invalid code with regard to reference counting. This application intercepts the reference counting calls and tries to detect invalid behavior. It supports a filter-rule mechanism to let you trace only the objects you are interested in and it can be used together with GDB.

Note that if GObject has been compiled with `--enable-debug=yes`, it exports a trap variable

    static volatile GObject *g_trap_object_ref;

If set to a non-NULL value, g_object_ref() and g_object_unref() will be intercepted when called with that value.

## Writing API docs

The API documentation for most of the GLib, GObject, GTK+ and GNOME libraries is built with a combination of complex tools. Typically, the part of the documentation which describes the behavior of each function is extracted from the specially-formatted source code comments by a tool named gtk-doc which generates DocBook XML and merges this DocBook XML with a set of master XML DocBook files. These XML DocBook files are finally processed with xsltproc (a small program part of the libxslt library) to generate the final HTML output. Other tools can be used to generate PDF output from the source XML. The following code excerpt shows what these comments look like.

    /**
     * gtk_widget_freeze_child_notify:
     * @widget: a #GtkWidget
     *
     * Stops emission of "child-notify" signals on @widget. The signals are
     * queued until gtk_widget_thaw_child_notify() is called on @widget.
     *
     * This is the analogue of g_object_freeze_notify() for child properties.
     **/
    void
    gtk_widget_freeze_child_notify (GtkWidget *widget)
    {
    ...

Thorough documentation on how to set up and use gtk-doc in your project is provided on the GNOME developer website.