2_class_based.py

from typing import TypedDict


class Movie(TypedDict):
    name: str
    year: int


# Movie is a TypedDict type with two items: 'name' (with type str) and 'year' (with type int).
# Constructor as an ordinary dictionary type
movie: Movie = {"name": "Harry Potter ", "year": 2001}

# TypedDict types are callable at runtime and can be used
# as a constructor to create values that conform to the TypedDict type.
# The constructor takes only keyword arguments,
# corresponding to the items of the TypedDict. Example:
m = Movie(name="Blade Runner", year=1982)


# define a function to accept TypedDict
def func(movie: Movie) -> None:
    print(f"printing the type {type(movie)}")  # it is  type <class 'dict'>
    print(f"Movie name {movie['name']}")  # obtain the value of the  type "name"
    print(movie)  # {'name': 'Blade Runner', 'year': 1982}
    print(type(movie))  # <class, dict>


# call the function with created Movie type object
func(movie)

# call the function with inline argument passing
func({"name": "Blade Runner", "year": 1982})


# define function which return Movie data type
def func2(arg1: str, arg2: int) -> Movie:
    return Movie(name=arg1, year=arg2)


myMovie: Movie = func2("Gone with the wind", 1995)
print(myMovie)  # {'name': 'Gone with the wind', 'year': 1995}


# Inheritance :
# This creates a TypedDict type BookBasedMovie
# with three items: 'name' (type str), 'year' (type int), and 'based_on' (type str)
class BookBasedMovie(Movie):
    based_on: str


def func3(bookstore: BookBasedMovie) -> None:
    pass


# More examples . You see how we create a new type called Point2D
class Point2D(TypedDict):
    x: int
    y: int
    label: str

# We inherited from Point2D and added one type called "z"
class Point3D(Point2D):
    z: int


a: Point2D = {"x": 1, "y": 2, "label": "good"}  # OK

# TypedDict  and Dict are the same 
assert Point2D(x=1, y=2, label="first") == dict(x=1, y=2, label="first")  # ok;

#Type "dict[str, int | str]" is not assignable to declared type "Point3D"
# "x" is required in "Point3D"
#  "y" is required in "Point3D"
# "x" and "y" type are mandatory to include by default as per original PEP
b: Point3D = {"z": 3, "label": "bad"}  # Fails