[Python-Dev] transitioning from % to {} formatting (original) (raw)

Raymond Hettinger python at rcn.com
Thu Oct 8 19:14:19 CEST 2009

[Christian Tanzer]

How do you suppose that maintainers could ever do the transition from %- to {}-formatting manually?

[Guido van Rossum]

This is pretty much the situation with integer division (you can only recognize it by running the code),

Do you think there may be some possible parallel to the -3 option to flag cases of %-formatting? If so, that could be helpful.

So, yes, we will continue to make noise about this. And yes you should opportunistically migrate your code to {}-formatting, like when you're rewriting some code anyway. One of the nice things about {}-formatting is that in most cases (things like the logging API excluded) you can change it one format string at a time.

I've already have some code that mixes the styles (using {} for new stuff).

Raymond

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