Class constructor list remains empty throughout Python code

Question

I am trying to implement a stack, then use a module called reverse_list to add something to the stack using a prebuild push module within the stack class, and then pop it out of the stack in to a list, then add it back to the stack and return it. But when i run the function it looks like the items do not get properly added to the property self.items, as the debugger shows that it forever remains at "[]", which is not a desired result, which also means it skips the other functions that require the list to be anything but empty.

my_list = [1, 2, 3, 4, 5]

class Stack:

    def __init__(self):
        self.items = []

    def push(self, item):
        if type(item) == list or type(item) == tuple:
            for items in item:
                self.items.append(items)
        else:
            self.items.append(item)

    def pop(self):
        self.items.pop()

    def reverse_list(self, arr):

        classer = Stack()
        classer.push(my_list)
        temp_list = []
        while self.items:
            temp_list.append(self.items.pop())
        for elements in temp_list:
            self.items.append(elements)
        return self.items


if __name__ == "__main__":
    starter = Stack()
    print(starter.reverse_list(my_list))

Current output: []

Desired output: [5, 4, 3, 2, 1]

Danke

khelwood · Accepted Answer · 2020-02-21 08:22:35Z

4

Inside reverse_list you make another instance of Stack and you push your list onto that. But that other instance is not self, so self.items is still empty.

I think you want to get rid of classer and just use self.

answered Feb 21, 2020 at 8:22

khelwood

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