The stack implementation in Python utilizes a simple class-based structure that adheres to the Last-In-First-Out (LIFO) principle, where the most recently added item is the first to be removed. This stack is represented by a list, allowing efficient addition and removal of elements from the top of the stack.
The Stack class begins with an initializer method, __init__, which sets up an empty list, self.stack. This list represents the stack where items will be added or removed. The initializer ensures that each instance of Stack starts with a clean slate, free of any elements.
The push method adds an element to the stack by appending it to the end of self.stack. Appending to a list in Python is an O(1) operation, making it efficient for this purpose. The method accepts a single parameter, item, which is the element to be pushed onto the stack. After appending, a message is printed to confirm the successful addition of the item.
The pop method handles the removal of the top element from the stack. Before attempting to remove an item, it checks if the stack is empty using the is_empty helper method. If the stack is not empty, it removes the last item in self.stack and returns it, providing a way for external code to access the removed element. If the stack is empty, it displays an error message to indicate that there are no items to pop, returning None to handle the edge case gracefully.
The peek method allows users to view the top element without modifying the stack. Similar to pop, it first checks if the stack is empty. If not, it returns the last element of self.stack. If the stack is empty, it prints a message indicating that there are no items to peek at.
The is_empty method checks if the stack contains any items by evaluating the length of self.stack. This method returns a Boolean value, where True indicates an empty stack, and False indicates otherwise.
Overall, this stack implementation provides a simple, efficient way to perform core stack operations with a clear output for each action, enhancing usability and error handling.