This document is somewhat outdated, it exists now in a project called Rat. Check it out!

Working with GConf is usually a repetitive task, you must make sure each key has the correct value type, synchronize it with your widget's data (and vice-versa), make the widget insensitive if the key is not writable, etc. GAW tries to solve this problem in an out-of-your face manner. GAW is a Python module to be used with PyGtk.

Unlike gconf_widgets.py - which is used in gnome-blog, GAW doesn't redefine widgets, it takes a different approach and uses existing widgets. For example gconf_widgets.py can't cope with LibGlade pre-generated widgets, whereas GAW can. It also has a different license, LGPL.

Let's begin with a simple example, we'll try to bind a gtk.Entry to a GConf key, /apps/gaw/str_key:

  import gaw, gtk, gconf
  # Monitor the key, so gaw can listen for gconf events
  gconf.client_get_default ().add_dir ("/apps/gaw", gconf.CLIENT_PRELOAD_NONE)
  win = gtk.Window (gtk.WINDOW_TOPLEVEL)
  entry = gtk.Entry ()
  entry.show ()
  # bind the key with the widget
  gconf_data = gaw.data_entry (entry, "/apps/gaw/str_key")
  win.add (entry)
  win.show ()
  gtk.main ()

As you can notice is pretty straightforward, gaw.data_entry creates an integrity binding between the key and the widget, this binding is always in favor of the widget.

The gaw.data_entry method is just a wrapper function for calling a more generalized class called gaw.Data, this is the real binding between the two parts. The gaw.Data uses another class called gaw.GConfValue, so in order to explain how gaw.Data works we need to explain what is a gaw.GConfValue.

A gaw.GConfValue is a simple representation of a GConf key, it wraps around it and provides three important features:

• a callback to when the GConf key is changed
• a way to retrieve the GConf directly, whichever the type is
• a way to retrieve default values when the key is invalid or non existant

To setup a callback you merely use the gaw.GConfValue.set_callback method which wraps around gconf.Client.notify_add method but with the appropriate key.

To retrieve or set the value of that key you just access the member gaw.GConfValue.data.

Let's look at an example of it's usage:

  import gaw, gconf, gtk
  gconf.client_get_default ().add_dir ("/apps/gaw", gconf.CLIENT_PRELOAD_NONE)
  key_str = gaw.GConfValue (
      key = "/apps/gaw/key_str",
      data_spec = gaw.Spec.STRING
  )
  def on_changed (*args):
      global key_str
      print key_str.key, "=", key_str.data
      gtk.main_quit ()
  tmp.set_callback (on_changed)
  tmp.data = "Hello world"
  gtk.main ()

The gaw.Spec.STRING is the definition of the key type, there are the following specs: STRING, FLOAT, INT and BOOL.

Next we set the callback and print the key and it's contents, so as you can see it's really simple.

Now onto gaw.Data this is a really generic class so it's constructor is a bit verbose:

  gaw.Data (widget, widget_getter, widget_setter, changed_signal, gconf_value)

So the code behind gaw.data_entry is the one liner:

  def data_entry (entry, key, data_spec = Spec.STRING, default = None, client = None):
  	return Data (entry, entry.get_text, entry.set_text, "changed", GConfValue (key, data_spec, default, client))

Nothing better then a real life example to understand it's usage. As you can notice the widget_setter and widget_getter are self explanatory, they are functions that can set/get the data from your widget. The signal is the way the gaw.Data has to know that your widget's data has been changed.

gaw.py

Tags used:

• python
• gconf
• gnome