Python string.replace equivalent (from Javascript) -

i trying pick python , coming javascript haven't been able understand python's regex package re

what trying have done in javascript build very simple templating "engine" (i understand ast way go more complex):

in javascript:

var rawstring =    "{{prefix_helloworld}}   testing this. {{_thiswillnotmatch}} \    {{prefix_okay}}";  rawstring.replace(    /\{\{prefix_(.+?)\}\}/g,    function(match, innercapture){      return "one rule all"; }); 

in javascript result in:

"one rule testing this. {{_thiswillnotmatch}} 1 rule all"

and function called twice with:

   innercapture === "helloworld"    match ==== "{{prefix_helloworld}}" 

and:

   innercapture === "okay"    match ==== "{{prefix_okay}}" 

now, in python have tried looking docs on re package

import re 

have tried doing along lines of:

match = re.search(r'pattern', string) if match:   print match.group()   print match.group(1) 

but doesn't make sense me , doesn't work. one, i'm not clear on group() concept means? , how know if there match.group(n)... group(n+11000)?

thanks!

python's re.sub function javascript's string.prototype.replace:

import re  def replacer(match):     return match.group(1).upper()  rawstring = "{{prefix_helloworld}}   testing this. {{_thiswillnotmatch}} {{prefix_okay}}" result = re.sub(r'\{\{prefix_(.+?)\}\}', replacer, rawstring) 

and result:

'helloworld   testing this. {{_thiswillnotmatch}} okay' 

as groups, notice how replacement function accepts match argument , innercapture argument. first argument match.group(0). second 1 match.group(1).