Question

What is the specific method to iterate a stack in python. is the best practice to use a for loop just like to iterate a list?

Answer 1

As the others have said, python doesn’t really have a built-in stack datatype, per se– but you can use a list to emulate one.

When using a list as a stack, you can model the first-in-last-out behavior with append() as push and pop() as pop, as julio.alegria describes.

If you want to use that list in a for-loop, but still have it behave in the FILO fashion you can reverse the order of the elements with this slice syntax: [::-1].

Example:

for element in stack[::-1]:
    print element

If you’re using a custom class that implements a stack, just as long as it has __iter__() and next() methods defined you can use it in list comprehensions, for loops, or whatever.

That way you can implement a custom iterator that removes items as it iterates over it, just as it should with a proper stack.

Example:

class Stack:
    def __init__(self):
        self.data = []
    def push(self,n):
        self.data.append(n)
    def pop(self):
        return self.data.pop()
    def __iter__(self):
        return self
    def next(self):
        if len(self.data)>0:
            return self.pop()
        else:
            raise StopIteration

filo = Stack()
filo.push(1)
filo.push(2)
filo.push(3)

for i in filo:
    print i