[Vala] non-gobject property notify attribute

[pancake <pancake youterm com>]

It is possible to define a notification attribute for a variable in 
vapi/vala?

I would like to make vala generate a call to a function everytime a 
variable is accessed.

This is something like properties (get/set..) but at vapi level. This 
way it will be
possible to 'notify' when a variable has changed by calling a delegate 
or so without
having to use gobject.

In fact, the generated stub can be a setter that changes the value of 
the variable
and executes a lambda/delegate function by passing the 'this' pointer 
if inside a class.

--pancake