Passing comparison operators in Python

approach_1.py

## approach 1

def myfun(a, b, mode='<'):
  valid_modes = ['<', '<=', '>', '>=', '==', '!=']
  if mode not in valid_modes:
    print 'Error!'
    ... # error handling code here
    return
  if mode == '<':
    if a < b:
      ...
  elif mode == '<=':
    if a <= b:
      ...
  elif mode == '>':
    if a > b:
      ...
  elif mode == '>=':
    if a >= b:
      ...
  elif mode == '==':
    if a == b:
      ...
  elif mode == '!=':
    if a != b:
      ...
  else:
    print 'Something went horribly wrong.  Blame cosmic rays.'

approach_2.py

## approach 2

# comparators
cmp_lt = lambda x,y: x < y
cmp_gt = lambda x,y: x > y
cmp_eq = lambda x,y: x == y
cmp_lte = lambda x,y: x <= y
cmp_gte = lambda x,y: x >= y
cmp_neq = lambda x,y: x != y

def myfun(a, b, comparator):
  if comparator(a,b):
    ...

approach_3.py

## python is batteries included!

import operator

def myfun(a, b, comparator):
  if comparator(a,b):
    ...

approach_4.py

## don't do this, dummy

def myfun(a, b, mode='<'):
  if eval(str(a)+mode+str(b)):
    ...