How to set a class inheritance at instance creation?

[Stargaming]

glomde schrieb:
> Hi I wonder if you can set what subclass a class should
> have at instance creation.
> 
> The problem is that I have something like:
> 
> class CoreLang():
>     def AssignVar(self, var, value):
>          pass
> 
> class Lang1(CoreLang):
>      def AssignVar(self, var, value):
>           return var, "=", value
> 
> class Lang2(CoreLang):
>      def AssignVar(self, var, value):
>           return var, "<=", value
> 
> class WriteStruct():
>      def Generate(self, vars):
>         for var in vars:
>              print self.AssignVar()
> 
> The problem is that I want  WriteStruct to sometimes be a subclass of
> Lang1 and sometimes
> of Lang2.
> In the above example I could but the Generate Method in CoreLang. But
> in my real
> example I also want to able to subclass WriteStruct to be able to easy
> customize WriteStruct.
> Which I wouldnt be able to do if it was a method in CoreLang.
> 
> So in code I would like to write something like:
> 
> WriteStruct(Lang1).Generate(vars)
> 
> Even better would be that if I in the Lang1 class could
> just do WriteStruct().Generate(vars) and Lang1 class would
> magically make WriteStruct a subclass of itself.
> 
> 
> Cheers,
> 
> /T
> 

If you really need to inherit at runtime, you could utilize `type()`.

 >>> def foo(self, blah):
...   print self, blah
...
 >>> attrs = {'foo': foo}
 >>> cls = type('MyCls', (object,), attrs)
 >>> cls().foo(4)
<__main__.MyCls object at 0x009E86D0> 4

Changing ``object`` (the tuple contains all bases) will change the 
parent. But, better stick to previous solutions. :)

Stargaming