Joe Mosby's blog

Hacking __builtin__ for fun, no profit

Python's __builtin__ module contains all of the language's built-in functions, which should be reasonably obvious from the name. Python is really, really insistent that its built-ins are perfectly sufficient and that you shouldn't go around messing with them. This is a large part of the reason that I almost threw up the first time I had to go monkeypatching in Ruby... it just doesn't feel right. But for the sake of argument, let's do some screwing around with the built-in functions.

import __builtin__

def hex(x):
	'''Return the basic hex function, but with extra YOLO attached.'''
	f = __builtin__.hex(x)
	if f[0] == '-':
		return f[0] + 'yol' + f[1:]
		return 'yol' + f

The hex function is designed to return the hexadecimal representation of an integer, prefixed with 0x. I felt like this representation could be much improved with a bit of extra YOLO, and patched the function accordingly. Now I can call hex(255) and receive back "yol0xff", a marked improvement over the prior implementation.

import __builtin__

def len(s):
	'''Return the basic len function, but subtract one so we show what the last position number is.'''
	l = __builtin__.len(s)
	return l-1

I'm lazy, and don't always like to calculate the length of a list or string then subtract one to access the last element of a list. Why not ask len() to do that work for me? Now I can call len('hello') and receive a value of 4, allowing me to easily determine the number of the last character any time and every time.

Okay, okay... I can think of no reason why any programmer would want to go messing around with the __builtin__ library. It would be horribly un-Pythonic to start wrapping the core Python functions like this. But it's good to know that we can.