Module GUtil

Utility classes for programming with GTK objects

The memo class provides an easy way to remember the real class of a widget. Insert all widgets of class in one single t memo, and you can then recover their original ML object with #find.

The ML signal mechanism

It allows one to add GTK-like signals to arbitrary objects.

As with GTK signals, you can use GtkSignal.stop_emit inside a callback to prevent other callbacks from being called.

To add ML signals to a LablGTK object:

class mywidget_signals obj ~mysignal1 ~mysignal2 = object
  inherit somewidget_signals obj
  inherit add_ml_signals obj [mysignal1#disconnect; mysignal2#disconnect]
  method mysignal1 = mysignal1#connect ~after
  method mysignal2 = mysignal2#connect ~after
end

class mywidget obj = object (self)
  inherit somewidget obj
  val mysignal1 = new signal obj
  val mysignal2 = new signal obj
  method connect = new mywidget_signals obj ~mysignal1 ~mysignal2
  method call1 = mysignal1#call
  method call2 = mysignal2#call
end

You can also add ML signals to an arbitrary object; just inherit from ml_signals in place of widget_signals+add_ml_signals.

class mysignals ~mysignal1 ~mysignal2 = object
   inherit ml_signals [mysignal1#disconnect; mysignal2#disconnect]
   method mysignal1 = mysignal1#connect ~after
   method mysignal2 = mysignal2#connect ~after
 end

Propagating state modifications

The variable class provides an easy way to propagate state modifications. A new variable is created by new variable init. The #set method just calls the set signal, which by default only calls real_set. real_set sets the variable and calls changed when needed. Deep equality is used to compare values, but check is only done if there are callbacks for changed.