How to query number of positional arguments to "".format()

Asked Jun 19 '15 at 13:58

Active Jun 19 '15 at 13:58

Viewed 19 times

I'm looking for a way to determine how many positional arguments a string has when used with format().

For example:

>>> "{0}, {1} {0}".format("Bond", "James")
Bond, James Bond
>>> number_of_positionals("{0}, {1} {0}")
2
>>> number_of_positionals("{0}, {key} {1} {2}")
3

I can implement number_of_positionals myself, but not being fully familiar with all the ins and outs of the format() mini-language, I'm worried about missing out on edge-cases.

Is there a built-in or otherwise solid implementation of this available in Python 2.6 or 2.7?

asked Jun 19 '15 at 13:58

Marcus Ottosson

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See [`string.Formatter.parse`](https://docs.python.org/2/library/string.html#string.Formatter.parse) – Peter Wood Jun 19 '15 at 14:00
Thanks @PeterWood, I had a look but I can't figure out what it does or how it can be used to solve the problem.. could you provide an example? – Marcus Ottosson Jun 19 '15 at 14:07
See the second answer to the duplicate question. – Peter Wood Jun 19 '15 at 14:35
Found it, thanks Peter! – Marcus Ottosson Jun 19 '15 at 16:26

How to query number of positional arguments to "".format()

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