decorators - would be nice if...

Ken Seehart ken at seehart.com
Tue Jul 14 23:44:51 CEST 2009


Almost every time I use decorators, I find myself wishing I had access
to the local namespace of the context from which the decorator is
executed.  In practice, decorator is being applied to a method, so the
namespace in question would be the dictionary of the class being created.

Similarly, before decorators were around, I often found myself lamenting
the fact that a class is not created until after it's scope is
completed, since this makes certain kinds of metaprogramming more
difficult.  But after digging deeper, I realized why it is the way it
is, so I don't complain about that.

But it would have been a simple thing to add an argument 'locals' to the
decorator specification.  It's somewhat more difficult to add that now
because of compatibility issues, but perhaps there is a way to get the
same effect.

I can work around all of this by making my decorators just store data to
be processed by a metaclass, but that solution is less elegant.  Also,
it has the slight disadvantage of requiring the use of a metaclass which
would otherwise not be necessary.  I prefer to save metaclass
implementation as a last resort for various reasons (e.g. there does not
seem to be a good way to use multiple metaclasses in a class hierarchy,
and more generally you can't stack them on top of each other (you can
only have one metaclass per class)).

Thoughts?

- Ken





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