PCPP2 Design Patterns Practice Question
You are implementing the Command pattern. How can you best support the 'Undo' operation for a command that changes a document's state?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Store the delta or previous state information within the concrete command instance
The Command object must store the previous state or the inverse operation before performing the change, allowing it to revert the state later.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Store the delta or previous state information within the concrete command instance
Why this is correct
Storing enough information to reverse the operation is the standard way to implement Undo in the Command pattern.
- ✗
Use the Python 'copy' module to clone the document before every command
Why it's wrong here
Cloning is expensive and doesn't explicitly store the logic required for reversal.
- ✗
Store the entire document object in the command history
Why it's wrong here
This is memory-intensive and inefficient for large documents.
- ✗
Re-execute the entire command history up to the point of the undo
Why it's wrong here
Re-executing the entire history is inefficient and complex.
About these practice questions
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Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Python Institute exam blueprint
This PCPP2 practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCPP2 exam.