Simplifying anonymous inner classes?

Tim Chase python.list at tim.thechases.com
Mon Nov 3 16:49:33 CET 2008


>> Is there a more Pythonic way to instantiate sub-classes and
>> provide instance-specific implementations without the
>> overhead of an unused "anonymous" class cluttering my
>> code/namespace?
> 
> I agree with Carl Banks that what you do is already fairly
> Pythonic: explicit is better than implicit, and simple is
> better than complex. What you do *is* simple, and easy to read
> - no magic involved. You wish it to be more concise - but I
> think that would make *less* pythonic, not more.

After playing with the various solutions (hurray for 
version-control), I find myself back where I started, agreeing 
with Carl & Martin for the most part.  Everything else ended up 
looking so baroque that it made matters worse.  Even the extra 
"del" statements for cleaning up the namespace were extra clutter 
in the code, so I didn't bother tidying the namespace.  I did 
switch from

   do_foo = _Foo(args)
   do_bar = _Bar(args)

to having each backend contain a list of available actions, so I 
simply maintain

   self.actions = set([
     _Foo(args),
     _Bar(args),
     _Baz(args),
     ])

(each Action knows how to hash itself for entry in a set) and 
then descendants of Backend (such as DBBackend) simply add to 
this set of actions in their own __init__ call.

The final product is what I'd call a "most understandable/least 
convoluted" solution which, in the big picture, seems to be a 
good part of "pythonicity".  Until such time as Python offers 
anonymous classes natively :)

Thanks to all who offered suggestions.

-tkc







More information about the Python-list mailing list