Understanding the Call Stack

Warmup

• What is a stack trace?

Data Structures

• Abstract model for organizing data
• Models relationships between data
• Models inserting and accessing data
• Can model other things, for example:
  • searching
  • deleting

Common Data Structures

• Linked List
• Binary Tree
• Graph
• Heap
• Stack

Stacks

• Fundamental Data Structure in computer science
• A Stack is the opposite of a Queue
• Follows “first-in-last-out” semantics
• Important point about a stack: Things on top of the stack cover or hide things on the bottom – you can’t see or access lower elements while there is a top element

Terminology

• Top - Most recently added element (sometimes people will say “bottom” if they are envisioning the stack growing from top down)
• Pushing - adding a new element to the top of the stack
• Popping - removing the top element from the stack

The Call Stack

• Represents each method called as an element on the stack.

Explorations

See lesson plan.

Check for Understanding

• What is the Stack data structure? What are the rules of interacting with a Stack?
• What is The Call Stack? How does it work?
• What is a return value, in terms of The Call Stack?
• When an error occurs, how does Ruby create the Stack Trace?