[IronPython] __init__ ignored in favor of base class constructor? - blocker

Dan Eloff dan.eloff at gmail.com
Sun Nov 30 16:42:51 CET 2008

On Sun, Nov 30, 2008 at 8:30 AM, Michael Foord
<fuzzyman at voidspace.org.uk> wrote:
> Hello Dan,
> I can't find this assembly to experiment - but when you subclass a .NET type
> in IronPython you override the constructor by overriding '__new__' and not
> '__init__'. Perhaps this is the cause of your problem? (If the default
> constructor takes two arguments then merely supplying an __init__ method
> that only takes one won't stop the default two argument constructor being
> called.)

I don't think I've ever subclassed a .NET type that has a default
constructor taking an argument, hopefully the problem here is with me
and not IronPython :) I thought __new__ might be the one to use, but I
got these errors with __new__:

class MyTheme(Theme):
    def __new__(cls):
        return Theme.__new__(cls,
Application.GetResourceStream(Uri('theme.xaml', UriKind.Relative)))

TypeError: default __new__ does not take parameters.

If I use:

class MyTheme(Theme):
    def __new__(cls):
        return Theme.__new__(cls)

TypeError: MyTheme() takes at least 2 arguments (1 given)

Back to square one. Do you have some idea what I'm doing wrong here?
The assembly is from the Silverlight Toolkit:


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