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Throughout the chapter, a running example of a file viewer program is used, which has a ViewerFile class to represent a single file being viewed, and various derived classes for different types of files with special functionality, such as audio files.
The example application also supports editing files for example, to tweak a photo being viewed , using a ViewerEditable interface. The first step before writing the code for your GObject is to write the type's header which contains the needed type, function and macro definitions.
Each of these elements is nothing but a convention which is followed by almost all users of GObject, and has been refined over multiple years of experience developing GObject-based code. If you are writing a library, it is particularly important for you to adhere closely to these conventions; users of your library will assume that you have. Even if not writing a library, it will help other people who want to work on your project. Do not separate the prefix from the typename: viewerfile.
Some people like the first two solutions better: it makes reading file names easier for those with poor eyesight. The recommended method of declaring a type differs based on whether the type is final or derivable. Final types cannot be subclassed further, and should be the default choice for new types — changing a final type to be derivable is always a change that will be compatible with existing uses of the code, but the converse will often cause problems.
Derivable types can be subclassed further, and their class and instance structures form part of the public API which must not be changed if API stability is cared about. The convention for header includes is to add the minimum number of include directives to the top of your headers needed to compile that header.
This allows client code to simply include "viewer-file. Go to page content Go to main menu Go to the search field. About Users Administrators Developers. How to define and implement a new GObject. Boilerplate header code Boilerplate code Object construction Object destruction Object methods Non-virtual public methods Virtual public methods Virtual private Methods Chaining up.
Boilerplate header code. This website is available in many languages Switch Language. Hosted by Red Hat.
The GObject. GObject class provides methods for object construction and destruction, property access methods, and signal support. A native GObject is accessible via GObject. It is rarely instantiated directly, we generally use inherited class. A Gtk.
GObject basic concepts
This document is released under the terms of the FDL. GNOME GNU Network Object Model Environment is a project whose main goals are to create a complete, free and easy-to-use desktop environment for users as well as a powerful application development framework for software developers. As a result of this second goal GNOME is based on a set of libraries which are very easy to access from a large amount of programming languages. But this does not mean that you can not program in an Object Oriented way with C, it's only that you have to do some extra work.
The GLib Object System , or GObject , is a free software library providing a portable object system and transparent cross-language interoperability. GObject is designed for use both directly in C programs to provide object-oriented C-based APIs and through bindings to other languages to provide transparent cross-language interoperability, e. Though GObject has its own separate set of documentation  and is usually compiled into its own shared library file, the source code for GObject resides in the GLib source tree and is distributed along with GLib. At the most basic level of the GObject framework lies a generic and dynamic type system called GType. The GType system holds a runtime description of all objects allowing glue code to facilitate multiple language bindings. The type system can handle any singly inherited class structure, in addition to non-classed types such as opaque pointers , strings , and variously sized integers and floating point numbers.