Type Hints Examples

[loganthomas]

• List of type hints examples for reference

• Notes:

  • Including type hints are a way to "self-document" code.
  • Since Python will always be a dynamically typed language (the authors have no desire to ever make type hints mandatory, even by convention), failure to abide by type hints will never cause a run time error.
  • However, they will help developers when using the code in an IDE if they have a static checker set up.

• Example consider the add_ints() function below:

def add_ints(x: int, y: int) -> int:
    return x + y

• Since Python will always remain a dynamically typed language, all the below lines of code will run without error.

print(add_ints(5, 5))
# yields => 10

# This will run without error even though x and y are floats
print(add_ints(5.5, 3.5))
# yields => 9.0

# This will run without error even though x and y are strings
print(add_ints('a', 'b'))
# yields => 'ab'

• But, with a static type checker installed in my IDE, I will get the below errors:

• The help() builtin function will also show type hints:

help(add_ints)

Help on function add_ints in module type_hints:

add_ints(x: int, y: int) -> int

[loganthomas]

Let me know if you'd like more examples. Happy to add some. Feel free to leave comments inline for things that are confusing. I think you'll like this 😄

[loganthomas]

Let me know if you'd like more examples. Happy to add some. Feel free to leave comments inline for things that are confusing. I think you'll like this 😄