%-style formatting method

[rrolls (Rob Rolls)]

@timhoffm

If not, the argument can only “people still want %-formatting in new code sometimes”. And then I argue they want it because of the %-placeholders, not because of the %-operator. A small and focussed addition of a .pformat() method would be a consistent alternative to the %-operator.
We could then write: “do not use the %-formatting operator for new code. In most cases you’ll want to use f-strings or the format() method instead. If you still want to use %-placeholder syntax, use the pformat() method instead.”

Yes, please. I would fully support this.

I personally will want to use %-placeholders for a very long time (til the day I die, perhaps?!), no matter what anyone else says - but I will be the first to say I never liked the %-operator.

Introducing the str.pformat() method, and immediately updating docs exactly as you suggest, would certainly make me happy, and in the long term it might even allow for str.__mod__ to be outright removed, solving the original problem raised in Deprecate str % format operator.

@Rosuav

Yes, [ pformat can be written as a standalone function in pure Python], and I suggested this exact solution early on:

def sprintf(fmt, *args):
   return fmt % args

It fixes the problems, at a whopping cost of two lines of code. I like percent formatting, I don’t like the quirks of the modulo operator, and this one function solves that for all three types (str, bytes, bytearray) polymorphically.

It does solve the “single tuple argument” problem, but putting together what has already been expressed in several separate posts above:

• it has to be added to everyone’s codebase;
• it’s inconsistent with str.format being a method; and
• it doesn’t provide a nice clear visual separator between format-string and args.

IMO the last reason here is why I don’t already use this solution. I’d prefer str.pformat over str.__mod__, but I’d prefer sticking with str.__mod__ over adding this function everywhere.