UKUUG Linux 2001 — Linux Developers' Conference 29 June - 1 July 2001, Renold Building, UMIST, Manchester

Christian Egli

Rapid Application Development with GNOME and Python

What is RAD?

RAD is a programming system that enables programmers to build working programs very quickly . In general, RAD systems provide a number of tools to help build graphical user interfaces that would normally take a large development effort. Two of the most popular RAD systems for Windows are Visual Basic and Delphi.

RAD and Free Software

With the combination of tools such as GNOME, Python, Glade and LibGlade the world of Free Software also offers an excellent RAD system. Each individual tool is powerful on its own, but it is in combination that new heights of rapid application development can be achieved.

Python

Python is an interpreted, interactive, object-oriented programming language. It is often compared to Tcl, Perl, Scheme or Java. It includes a rich set of standard libraries for things such as networking, standard database API and even XML-RPC. The bindings to the GNOME libraries are also exceptional.

GNOME

GNOME is well established as a desktop environment. However, GNOME also features a development platform which offers a multitude of libraries based on standard and open technologies, such as CORBA and XML. Using this platform allows the developer to write user-friendly and stable software both easily and efficiently.

Glade

Glade is _the_ GUI-Builder for GNOME. It allows straightforward and simple construction of Graphical User Interfaces and gives the developer access to all of the Gtk+ and GNOME widgets.

LibGlade

Usually Glade is used to generate C or C++ code directly. However, a XML representation of the GUI that was created can also be saved. With the help of LibGlade this XML file can be loaded at runtime of the program. LibGlade then recreates the GUI as it was designed in Glade.

Hands-on Demo

By writing a small application "gPizza" for the configuration of the hacker's favourite food, I demonstrate live how Python and GNOME can be used to create a running prototype in a very short time.

Highlights of the demo are:

• creation of the GUI with Glade
• introduction of the layout philosophy of Gtk+ and presentation of some of the Gtk+ and GNOME GUI Components
• attachment of widgets, i.e., their signals to Python callbacks
• use of the standard Python database API and a few more lines of Python code to connect to a database and fetch some rows that contain all the crucial information to configure pizzas.

Conclusion

The conclusion illuminates further possibilities, such as bonobo and gnome-db integration, and looks at the direction the above collection of tools is expected to take in the future.

Target audience

This talk is aimed at developers. It is, however, done in a tutorial style with the hope that anyone will be able to follow without any prior knowledge of GNOME or Python.

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