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[Python-Dev] decorator module patch

Nick Coghlan ncoghlan at gmail.com
Sun Mar 12 15:10:58 CET 2006 
Georg Brandl wrote:
> Hi,
> 
> to underlay my proposals with facts, I've written a simple decorator
> module containing at the moment only the "decorator" decorator.
> 
> http://python.org/sf/1448297
> 
> It is implemented as a C extension module _decorator which contains the
> decorator object (modelled after the functional.partial object) and a
> Lib/decorator.py to allow further decorators added as Python code.
> 
> Comes with docs and unit test.

Given that @decorator is a definition time only operation to modify a 
function's __name__, __doc__ and __dict__ attributes, and doesn't actually 
introduce any extra levels of run-time nesting to function calls, I'm not 
clear on why you bothered with a hybrid implementation instead of sticking 
with pure Python.

(To clarify what I mean: using the example in the doc patch, the extra layer 
of run-time nesting from @decorator's wrapper function applies only to the 
@logged decorator, not to the function 'print_nested'. If an application has a 
decorated function definition in a performance critical path, a little bit of 
extra overhead from @decorator is the least of its worries.)

Also, I thought we were trying to move away from modules that shared a name 
with one of their public functions or classes. As it is, I'm not even sure 
that a name like "decorator" gives the right emphasis.

In general, decorators belong in the appropriate domain-specific module 
(similar to context managers). In this case, though, the domain is the 
manipulation of Python functions - maybe the module should be called 
"metafunctions" or "functools" to reflect its application domain, rather than 
the coincidental fact that its first member happens to be a decorator.

Regards,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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             http://www.boredomandlaziness.org
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