This rule raises an issue when unused scope-limited definitions are found.

Why is this an issue?

When a class or function is defined in a parent function or method, it is only visible in this parent function or method’s scope. If the defined class or function is not used within this scope it is dead code (unnecessary, inoperative code) that should be removed.

Cleaning out dead code decreases the size of the maintained codebase, making it easier to understand the program and preventing bugs from being introduced.

Code examples

Noncompliant code example

def parent_function():
    def nested_function():  # Noncompliant: this function is never used in this scope.
        print("nested_function")

    class NestedClass:  # Noncompliant: this class is never used in this scope.
        def __init__(self):
            print("NestedClass")

Compliant solution

def parent_function():
    class NestedClass:
        def __init__(self):
            print("NestedClass")

    NestedClass()