post init call

[Ulrich Eckhardt]

Am 18.06.2012 09:10, schrieb Prashant:
> class Shape(object):
>     def __init__(self, shapename):
>         self.shapename = shapename
>         
>         
>     def update(self):
>         print "update"
> 
> class ColoredShape(Shape):
>     def __init__(self, color):
>         Shape.__init__(self, color)

Two things here:
1. You pass "color" as "shapename" to the baseclass' initialisation
function, which is a bit surprising.
2. You can use super(ColoredShape, self).__init__(color) or even
super(self).__init__(color).


> User can sub-class 'Shape' and create custom shapes. How ever user
> must call 'self.update()' as the last argument when ever he is
> sub-classing 'Shape'.
> I would like to know if it's possible to call 'self.update()'
> automatically after the __init__ of sub-class is done?

You might be able to, by hacking on the (meta?) class and how/when
things are constructed. I'm not sure how to approach that though.

What I would do is to use lazy initialisation, i.e. call update() when
it is actually needed. For that, you could create a decorator and put it
on all methods that require this initialisation.


Good luck!

Uli