Get keys from template

Question

I would like to get a list of all possible keyword arguments a string template might use in a substitution.

Is there a way to do this other than re?

Answer 1

If it's okay to use string.format, consider using built-in class string.Formatter which has a parse() method:

>>> from string import Formatter
>>> [i[1] for i in Formatter().parse('Hello {1} {foo}')  if i[1] is not None]
['1', 'foo']

See here for more details.