"KDevelop is a free, open source IDE (Integrated Development Environment) for MS Windows, Mac OS X, Linux, Solaris and FreeBSD. It is a feature-full, plugin extensible IDE for C/C++ and other programming languages. It is based on KDevPlatform, and the KDE and Qt libraries and is under development since 1998."
Building additional plugins
First: install dependency
The KDevelop Parser Generator in the official repositories () is required to build additional plugins. Plugins will not compile if this package is not installed beforehand.
The PHP plugin () from the official repositories provides autocompletion and other PHP-specific features.
Restart KDevelop 4 and you should now have improved PHP support, including autocomplete for both the PHP functions as well as for your project's functions and classes.
List of available plugins
As of June 18 2009, the following plugins are available from KDE's svn repository.