[Python-Dev] transitioning from % to {} formatting

Christian Tanzer tanzer at swing.co.at
Thu Oct 8 16:51:00 CEST 2009

Eric Smith wrote at Thu, 08 Oct 2009 10:24:33 -0400:

> Vinay Sajip wrote:
> > BTW I sent Eric a private mail re. the "0o" versus "0" issue, to see if it was
> > worth raising an enhancement request on the bug tracker using "O" to generate
> > compatible rendering for octals.
> I didn't get your message, could you resend?.
> I was thinking the same thing, but it seems like a transition step. I'd
> rather not keep such backward compatibility hacks (if you will) around
> for the long haul.  How about a flag (maybe '*') at the start of the
> format specification which says "operate in backward compatibility
> mode"? We could document it as being only useful for the % to {}
> translator, and promise to remove it at some point in the future. Either
> actually deprecate it or just promise to deprecate it in the future.

That doesn't seem very useful to me. IIUC, the point of the translator
is to allow porting of the millions of existing %-formating operations
to the new-style .format.

If the result of that is deprecated or removed a few years from now,
all maintainers of long existing code have exactly the same problem.

IMHO, either the translation is done once and gives identical output or
it isn't worth doing at all.

Christian Tanzer                                    http://www.c-tanzer.at/

More information about the Python-Dev mailing list