[issue5965] Format Specs: doc 's' and implicit conversions

[Łukasz Rekucki]

Łukasz Rekucki <lrekucki at gmail.com> added the comment:

I see a problem with silently converting types without __format__() using str(). The user may write `"{:10s}".format(some_obj)`, which will work as long as some_obj doesn't have a formatter of it's own. If I later on, decide I want to add some custom formating to that object, there is a large chance I'll break a lot of code, 'cause doing it in backward-compatible way seems very difficult.

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nosy: +lrekucki

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue5965>
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