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 variant I would recommend:

mappings = {'A': 1, 'B': 2}  # Or whatever ...
def evaluate(match):
    return str(eval(match.group(0)[2:-1], mappings))
newstring = sub(r'\#\{([^#]+)\}', evaluate, string)

i.e. simply put the def evaluate(..) just before the sub(), as a local function.