How to pass a variable to a re.sub callback?

Question

I am using a re.sub callback to replace substrings with random values, but I would like the random values to be the same across different strings. Since the re.sub callback does

Answer 1

The easiest way I guess is to make use of functools.partial, which allows you create a "partially evaluated" function:

from functools import partial

def evaluate(match, mappings):
    return str(eval(match.group(0)[2:-1], mappings))

mappings = {'A': 1, 'B': 2}  # Or whatever ...

newstring = sub(r'\#\{([^#]+)\}', partial(evaluate, mappings=mappings), string)