[Python-ideas] Added a function to parse str.format() mini-language specifiers
eric at trueblade.com
Mon Mar 16 15:23:25 CET 2009
I'd like to add a function (or method) to parse str.format()'s standard
mini-language format specifiers. It's hard to get right, and if PEP 378
is accepted, it gets more complex.
The primary use case is for non-builtin numeric types that want to add
__format__, and want it to support the same mini-language that the built
in types support. For example see issue 2110, where Mark Dickinson
implements his own version for Decimal, and suggests it be moved elsewhere.
This function exists in Objects/stringlib/formatter.h, and will just
need to be exposed to Python code. I propose a function that takes a
single str (or unicode) and returns a named tuple with the appropriate
values filled in.
So, is such a function desirable, and if so, where would it go? I could
expose it through the string module, which is where the sort-of-related
Formatter class lives.
It could be a method on str and unicode, but I'm not sure that's most
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