Larry Hastings wrote:
The problem: if you're currently in a nested class, you can't look up
variables in the outer "class scope".
For example, this code fails in Python 3:
class Outer:
class Inner:
class Worker:
pass
class InnerSubclass(Inner):
class Worker(Inner.Worker):
pass
It fails at the definition of Worker inside InnerSubclass. Python 3
can't find "Inner", in order to get to "Inner.Worker".
Adding "global Inner" just above that line doesn't help--it's not a
global.
Adding "nonlocal Inner" just above that line doesn't help either--I
suppose it's the /wrong kind/ of nonlocal. nonlocal is for nested
functions, and this uses nested classes.
You can tell me YAGNI, but I tripped over this because I wanted it.
It's not a contrived example. I actually use inner classes a lot; I
suppose I'm relatively alone in doing so.
Yes, I could make the problem go away if I didn't have nested inner
classes like this. But I like this structure. Any idea how I can
make it work while preserving the nesting and inheritance?
Thanks,
/larry/
class Outer:
class Inner:
class Worker:
pass
print 'Outer ', locals()
class InnerSubclass(Inner):
print 'InnerSubclass', locals()
class Worker:
pass
Outer {'__module__': '__main__', 'Inner': <class __main__.Inner at
0x963a7ac>}
InnerSubclass {'__module__': '__main__'}
I use myself nested classes a lot, but only as namespace / enum, meaning
there is no inheritance involved. I don't think that you can do what you
are trying to do.
Outer would actually be a module, not a class.
JM
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