[Python-Dev] PEP 460 reboot

Antoine Pitrou solipsis at pitrou.net
Tue Jan 14 20:23:03 CET 2014


On Tue, 14 Jan 2014 10:52:05 -0800
Guido van Rossum <guido at python.org> wrote:
> Would you rather raise an exception, truncate the
> value, or mess up the formatting? All languages newer than Fortran
> that I've used have chosen the latter, and I still agree it's a good
> idea.

Well that's useful when printing out human-readable stuff on stdout,
much less when you're emitting binary data that's supposed to conform
to a well-defined protocol. I expect bytes formatting to be used for
the latter, not the former.

(which also means, actually, that I don't think the fancy formatting
features - alignment, etc. - are useful at all for bytes; but it's
probably ok having them for consistency)

> Similar with infinities, NaN, or None. (Yes, it's embarrassing
> to have a website displaying 'null'. But isn't a 500 even *more*
> embarrassing?)

When it comes to type mismatch, though, an error is raised:

>>> "%d" % object()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: %d format: a number is required, not object

(instead of outputting e.g. repr(id(x)))

Regards

Antoine.




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