[Python-ideas] Factory functions (was: RE: time.wallclock() or other similar stuff)

M.-A. Lemburg mal at egenix.com
Wed Nov 3 10:13:49 CET 2010


Antoine Pitrou wrote:
> On Wed, 3 Nov 2010 13:26:27 +0800
> Kristján Valur Jónsson
> <kristjan at ccpgames.com> wrote:
>> And why are there factory functions in threading.py and not classes?
> 
> I'm not sure, but it looks like a poor man's way of discouraging
> subclassing.

You usually use factory functions if you only define an API that
can then be implemented in many ways.

With a class hierarchy you are always bound to one implementation
and moving from Python to C or providing different specifically
optimized implementations can become cumbersome.

ElementTree is another example that uses factory functions.

-- 
Marc-Andre Lemburg
eGenix.com

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