#!/usr/bin/env python
''' Tiny script to do perl -p -i -e -type replace on text in files '''

import sys
import re


def perl_dash_pie(in_exp, out_str, filename):
    in_reg = re.compile(in_exp)
    in_txt = open(filename, 'rt').read(-1)
    out_txt = in_reg.sub(out_str, in_txt)
    if in_txt != out_txt:
        open(filename, 'wt').write(out_txt)
        return True
    return False


usage = ('Usage: '
         '%s <str_to_replace> <replacement> <filename0> '
         '[<filename1> ...]')


if __name__ == '__main__':
    prog = sys.argv.pop(0)
    if len(sys.argv) < 3:
        raise OSError(usage % prog)
    in_reg = re.compile(sys.argv.pop(0))
    out_str = sys.argv.pop(0)
    for fname in sys.argv:
        if perl_dash_pie(in_reg, out_str, fname):
            print 'Changes in file %s' % fname