learn-python/src/functions/test_function_annotations.py at master · gyheo/learn-python

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"""Function Annotations.

@see: https://docs.python.org/3/tutorial/controlflow.html#function-annotations

Function annotations are completely optional metadata information about the types used

by user-defined functions.

Annotations are stored in the __annotations__ attribute of the function as a dictionary and have no

effect on any other part of the function. Parameter annotations are defined by a colon after the

parameter name, followed by an expression evaluating to the value of the annotation. Return

annotations are defined by a literal ->, followed by an expression, between the parameter list and

the colon denoting the end of the def statement.

"""

def breakfast(ham: str, eggs: str = 'eggs') -> str:

"""Breakfast creator.

This function has a positional argument, a keyword argument, and the return value annotated.

"""

return ham + ' and ' + eggs

def dinner(name: str, place: str = 'restaurant', people_number: int = 5) -> str:

return name, ' and ', place, ' and ', people_number

def test_function_annotations():

"""Function Annotations."""

assert breakfast.__annotations__ == {'eggs': str, 'ham': str, 'return': str}

assert dinner.__annotations__ == {'name': str, 'place': str, 'people_number': int, 'return': str}