[Python-Dev] Default constructor values (Re: [Python-checkins] python/dist/src/Doc/lib libfuncs.tex,1.134,1.135)

[M.-A. Lemburg]

Guido van Rossum wrote:
>>>Types with constructors that insist on an argument are problematic to
>>>generic code that tries to instantiate a type by simply calling it.
>>
>>Why on earth would you be trying to instantiate something
>>without having any idea what parameters are required?
> 
> It could be the other way though: something could have a protocol
> where you can pass in a factory function that's called without
> arguments, and maybe you'd like to be able to pass it a built-in
> type.  Something very close to this happened to me when testing Zope 3
> filesystem synchronization.

Very close is still not good enough :-)

I can't really believe that you're designing protocols that have
to call unknown factory functions to see whether they do something
particular or not.

If you really happen to have a need for this, why can't you
introduce factory functions which take care of your particular
use case ? I don't think it's common enough to risk accidental
progamming errors in other user's code.

-- 
Marc-Andre Lemburg
eGenix.com

Professional Python Software directly from the Source  (#1, Jun 13 2003)
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