[Python-Dev] PEP 3101: floats format 'f' and 'F'

Eric Smith eric+python-dev at trueblade.com
Wed Jul 16 19:30:24 CEST 2008

Guido van Rossum wrote:
> On Wed, Jul 16, 2008 at 7:35 AM, Eric Smith
> <eric+python-dev at trueblade.com> wrote:
>> Does anyone know why 'F' is the same as 'f'?  Wouldn't it make more sense to
>> either drop it, or make it convert the exponent to upper case (like 'E' and
>> 'G')?  Compatibility with %-formatting is the only reason I can think of to
>> keep up, but I get the sense we've given up on an automatic conversion from
>> %-formatting to str.format().  Plus, I can find no uses of '%F' in the
>> standard library.
> My best guess as to why 'F' is the same as 'f' is that somebody
> (could've been me :-) thought, like several others in this thread,
> that %f never prints an exponent. I agree that making it emit an 'E'
> when an exponent is used is the right thing to do. Do it now!

It shares code with %-formatting.  Change that, too?  I couldn't find 
any occurrences of %F in the stdlib.  Not that that's the entire 
universe, of course.

The change is slightly less elegant if I don't change %-formatting, but 
still doable, especially if the betas don't get cut today.

More information about the Python-Dev mailing list