Core · Module 5 · Lesson 3 of 6

Copy Semantics: Deep Copies and the Rule of Three

Fix a leaking buffer class with a deep copy constructor, copy assignment, and destructor, and learn when the Rule of Three demands all three.

ProAbout 11 minutes

By the end you can

Write a deep copy constructor that duplicates a heap buffer element by element
Implement copy assignment with self-assignment and exception safety
Explain when the Rule of Three requires custom copy and destruction

Builds on Constructors, Destructors and the Rule of Zero.

01 · A question first

You copy a contact list to sort it, and the original scrambles too. Both objects point at one buffer, and the first destructor frees memory the second still uses. What must a copy do so the two lists evolve independently and free memory exactly once?

Make a guess before you read on.

02 · The idea

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What's inside

Why copying the pointer copies nothing
How a deep copy duplicates each element
Why the Rule of Three groups these operations
What it costs and where it still breaks
Where it is used