Quick Check: Python Structural Pattern Matching

Check your understanding of match, capture and value patterns, class patterns, guards, and OR patterns.

7 questions ~5 min

Knowledge check

Check your understanding of match, capture and value patterns, class patterns, guards, and OR patterns.

You can retake this quiz whenever you like.

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When several case patterns could match, which case is selected first?

Python tests case blocks in order and selects the first successful pattern.
What does case _ do?

The wildcard pattern matches anything and does not bind a value.
What can case {"path": path} do when matching a mapping?

A mapping pattern can select the path key and bind its value; extra keys do not prevent the match.
When is a case guard evaluated?

The pattern must succeed before its guard expression is evaluated.
What does "yes" | "y" mean in a case pattern?

An OR pattern succeeds when any of its alternatives succeeds.
In a case pattern, what does a bare name such as READY do?

Bare names other than the wildcard _ are capture patterns. Use a dotted name such as State.READY to match a named value.
What does Point(x=x, y=y) do when used as a class pattern?

A class pattern checks the subject against the class and then matches the requested attributes; it does not instantiate an object.

Back to lesson Next: Python Annotations

When several case patterns could match, which case is selected first?