George Sakkis wrote:
> "Ron Adam" <[EMAIL PROTECTED]> wrote:
>
> > I'm trying to implement simple svg style colored complex objects in
> > tkinter and want to be able to inherit default values from other
> > previously defined objects.
> >
> > I want to something roughly similar to ...
> >
> > class shape(object):
> > def __init__(self, **kwds):
> > # set a bunch of general defaults here.
> > self.__dict__.update(kwds)
> > def draw(self, x=0, y=0, scale=1.0):
> > # draw the object
> >
> > hello = shape(text='hello')
> > redhello = hello(color='red')
> > largeredhello = redhello(size=100)
> > largeredhiya = largeredhello(text='Hiya!')
> > largeredhiya.draw(c, 20, 50)
> >
> >
> > I think this will need to require __new__ or some other way to do it.
> > But I'm not use how to get this kind of behavior. Maybe the simplest
> > way is to call a method.
> >
> > redhello = hello.makenew( color='red' )
>
> Just name it '__call__' instead of makenew and you have the syntax sugar you
> want:
>
> def __call__(self, **kwds):
> new = self.__class__(**self.__dict__)
> new.__dict__.update(kwds)
> return new
>
> Personally I would prefer an explicit method name, e.g. 'copy'; hiding the
> fact that 'shape' is a
> class while the rest are instances is likely to cause more trouble than it's
> worth.
>
> George
Symmetry can be achieved by making shape a factory function of Shape
objects while those Shape objects are factory functions of other Shape
objects by means of __call__:
def shape(**kwds):
class Shape(object):
def __init__(self,**kwds):
self.__dict__.update(kwds)
def __call__(self, **kwds):
new = self.__class__(**self.__dict__)
new.__dict__.update(kwds)
return new
return Shape(**kwds)
Kay
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