Python's re.VERBOSE let you write [1]

    a = re.compile(r"""\d +  # the integral part
                       \.    # the decimal point
                       \d *  # some fractional digits""", re.X)

Instead of

    a = re.compile(r"\d+\.\d*")

But that is as far as it goes for me. From that point, masking REGEX with additional layer of 10's of functions is not a wise move.

[1] http://docs.python.org/2/library/re.html#re.VERBOSE