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Python language

Shallow copy

A copy of a container whose elements are still references to the same nested objects.

Why interviewers ask about it

a.copy(), list(a) and {**d} are all shallow. Mutating a nested list shows through both copies. copy.deepcopy() fixes it and is far more expensive - know both facts.

Related terms

Mutable default argument

Writing def f(items=[]). The list is created once at definition time and shared across every call.

This term is part of the free Python Full-Stack interview preparation module - browse the full glossary for every definition.