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

Nick Coghlan ncoghlan at gmail.com
Sun Oct 4 10:23:06 CEST 2009

Brett Cannon wrote:
> No one is saying we should deprecate % any time soon on strings
> themselves or anywhere. This discussion is purely in regards to
> argparse and logging to transition *their* APIs over to {} formatting
> which would most likely involve some deprecation for *using* %
> formatting in those APIs. But % formatting on strings themselves is
> not directly being discussed here.

Actually, I think percent formatting and brace formatting should remain
fully supported peers for the life of 3.x (including in APIs such as
argparse and logging).

No matter how much we might like the new formatting system (and I
certainly prefer it), there's a long period of evangelisation and
performance improvements that needs to happen before we can
realistically start to deprecate percent formatting based APIs in any
way shape or form.

Until that happens, then users do have the right to dig in their heels
and say "look, the limitations on percent formatting really don't bother
us, certainly not enough to switch to a new formatting system".


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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