[issue20811] str.format for fixed width float can return a string longer than the maximum specified

[aubmoon]

aubmoon added the comment:

We will add extending the float class as another possible work around or
part of a work around. Our developers now have a few options to
choose from. I am not sure which approach will be preferred. thanks for all
of the quick replies. this was just an odd case that was encountered, so I
wanted the community to be aware of it. if and when to address it is above
my level.

On Saturday, March 1, 2014, Eric V. Smith <report at bugs.python.org> wrote:

>
> Eric V. Smith added the comment:
>
> I still think this is a special case that we won't "fix". And even if we
> did, you'd have to wait until 3.5.
>
> But instead of your solution, it might be easier to wrap your floats in a
> class that implements your version of format, based on float's format with
> some post-processing:
>
> class MyFloat(float):
>     def __format__(self, fmt):
>         s = float.__format__(self, fmt)
>         if s[1] == '0':
>             return s[0] + s[2:]
>         return s
>
> print(format(MyFloat(0.12345678), '+8.8'))
> print(format(MyFloat(1.12345678), '+8.8'))
>
> gives:
> +.12345678
> +1.1234568
>
> I've grossly simplified __format__, of course. And I'm using built-in
> format() instead of ''.format() (because it's less typing), but they use
> the same mechanisms. So:
>
> print('{}:"{:+10.8}"'.format('answer', MyFloat(0.12345678)))
>
> gives:
> answer:"+.12345678"
>
> ----------
>
> _______________________________________
> Python tracker <report at bugs.python.org <javascript:;>>
> <http://bugs.python.org/issue20811>
> _______________________________________
>

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