Python Regular Expression Substitution

I have a block of text, and for every regex match, I want to substitute that match with the return value from another function. The argument to this function is of course the matched text.

I have been having trouble trying to come up with a one pass solution to this problem. It feels like it should be pretty simple.

From stackoverflow

• Right from the documentation:

  >>> def dashrepl(matchobj):
  ...     if matchobj.group(0) == '-': return ' '
  ...     else: return '-'
  >>> re.sub('-{1,2}', dashrepl, 'pro----gram-files')
  'pro--gram files'
  

  esiegel : Damn, I just assumed that it could be a string in that function

• Python-agnostic: Match everything before and everything after your text to replace.

  /^(.*?)(your regexp to match)(.*)$/
  

  Then you have the next before and after the text you're going to replace. The rest is easy -- just insert the result of your function between the two strings.

  ΤΖΩΤΖΙΟΥ : The OP said "for every match", so you described only half of the algorithm. In any case, the appropriate answer has been given and chosen.