for_implementation.py

# implemention for (each) loop in python as a function.
# Example:
# forr([1,2,3], print) 
# is the same as
# for item in container:
#   print(item)


def forr(cont, func):
  """ forr(cont, func) == for x in cont: func(x) """
  iterator = iter(cont) # or iter.__cont__
  while True:
    try:
      func(next(iterator))
    except StopIteration:
      break

In [26]: class l:
    ...:     def __init__(self):
    ...:         self.ll = [1,2,3]
    ...:     def next(self):
    ...:         if self.ll:
    ...:             return self.ll.pop()
    ...:         raise StopIteration
    ...:     def __iter__(self):
    ...:         return self
    ...:     
    ...:     

In [27]: g = l()

In [28]: for i in g:
    ...:     print i
    ...:     
3
2
1