Hooking str.__getitem__ in Python

Question

Is there a way of hooking str.__getitem__?

Example:

I'd like to be capable of do:

>>> "this is a string"[[1,3,4]]
'hs '

passing a list to [] and get the items in that list.

A more realistic example:

class STR(str):
    pass

class INT(int):
    pass

It's easy to make that STR("a string")[1] or STR("a string")[INT(1)] return an STR instance.

I'd like to be capable to make "a non STR string"[INT(1)] return an STR instance.

Answer 1

Why hook an often-used internal function when you can

def get_characters (s, l):
  return "".join(s[i] for i in l)

>>> get_characters("this is a string", [1,3,4])
"hs "

Answer 2

Methods on objects defined in C cannot be monkeypatched. The best you can do is to use an external function to complete the task.

Answer 3

Try Ruby if you want to hack the language. The fact that some "programmer" who thinks he knows better than others how string or integer is supposed to behave cannot do this in Python is one of the reasons why Python is my favorite language.