add lesson #13 slides, code

Author: fantom-voronezh

README.md

@@ -14,6 +14,7 @@
 10. [Память, профилирование](lesson-10)
 11. [Логирование, отладка](lesson-11)
 12. [C-расширения](lesson-12)
+13. [Аннотация типов](lesson-13)
 
 
 ## Правила оформления домашек на github

lesson-13/hints_check.py

@@ -0,0 +1,159 @@
+from collections.abc import Iterable, Sequence
+from dataclasses import dataclass
+from typing import Generator, NewType, TypeVar, TYPE_CHECKING
+
+
+type UserData = dict[str, str | int]
+type OptUserData = UserData | None
+
+
+@dataclass
+class User:
+    user_id: str
+    name: str
+    age: int
+
+    def __bool__(self) -> bool:
+        return bool(self.user_id)
+
+
+@dataclass
+class Person(User):
+    pass
+
+
+def fetch_url(url: str) -> UserData:
+   return {
+       "user_id": "1234",
+       "name": "steve",
+       "age": 99,
+   }
+
+
+def get_user_data(user: User) -> OptUserData:
+    if not user:
+        return None
+
+    data = fetch_url(user.user_id)
+    return data
+
+
+def run_get_user_data() -> None:
+    user1 = User("1234", "steve", 99)
+    data1 = get_user_data(user1)
+    print(f"{user1=} got {data1=}")
+
+    data2: OptUserData
+
+    data2 = data1
+    print(f"{user1=} got {data2=}")
+
+    user3 = User("", "", 0)
+    data3 = get_user_data(user3)
+    print(f"{user3=} got {data3=}")
+
+    user4 = Person("5432", "woz", 1024)
+    data4 = get_user_data(user4)
+    print(f"{user4=} got {data4=}")
+
+
+Celsius = NewType("Celsius", float)
+Fareng = NewType("Fareng", float)
+
+
+def convert_c_to_f(temp: Celsius) -> Fareng:
+    return Fareng(temp * 9 / 5 + 32)
+
+
+def gen_temps(start: Celsius) -> Generator[Celsius, None, str]:
+    yield start
+    val = yield Celsius(start + 10)
+    yield Celsius(start + 15)
+
+    return "finish"
+
+
+def get_max_temp(temps: Iterable[Celsius]) -> Celsius | None:
+    if not temps:
+        return None
+
+    return max(temps)
+
+
+def get_first_temp(temps: Sequence[Celsius]) -> Celsius | None:
+    if not temps:
+        return None
+
+    return temps[0]
+
+
+def run_convert_c_to_f() -> None:
+    temp1 = Celsius(-40.0)
+    faren1 = convert_c_to_f(temp1)
+    print(f"{temp1=}, {faren1=}, {type(temp1)=}, {type(faren1)=}")
+
+    max_temp1 = get_max_temp([Celsius(-40.0), Celsius(5.1), Celsius(36.0)])
+    print(f"{max_temp1=}")
+
+    max_temp2 = get_max_temp([])
+    print(f"{max_temp2=}")
+
+    temps3: tuple[Celsius, ...] = (Celsius(-40.0), Celsius(5.1), Celsius(36.0))
+    max_temp3 = get_max_temp(temps3)
+    print(f"{max_temp3=}")
+
+    temps4 = gen_temps(Celsius(10.0))
+    max_temp4 = get_max_temp(temps4)
+    print(f"{max_temp4=}")
+
+    first_temp1 = get_first_temp([Celsius(-40.0), Celsius(5.1), Celsius(36.0)])
+    print(f"{first_temp1=}")
+
+    first_temp2 = get_first_temp([])
+    print(f"{first_temp2=}")
+
+    f_temps3: tuple[Celsius, ...] = (Celsius(-40.0), Celsius(5.1), Celsius(36.0))
+    first_temp3 = get_first_temp(f_temps3)
+    print(f"{first_temp3=}")
+
+    # f_temps4 = gen_temps(Celsius(10.0))
+    # first_temp4 = get_first_temp(f_temps4)
+    # print(f"{first_temp4=}")
+
+
+# T = TypeVar("T")
+
+
+def get_first_temp_generic[T](temps: Sequence[T]) -> T | None:
+    if not temps:
+        return None
+
+    return temps[0]
+
+
+def run_generic() -> None:
+    first_temp1 = get_first_temp_generic([Celsius(-40.0), Celsius(5.1), Celsius(36.0)])
+    print(f"{first_temp1=}")
+
+    first_temp2: Fareng | None = get_first_temp_generic(
+        [Fareng(-40.0), Fareng(5.1), Fareng(36.0)]
+    )
+    print(f"{first_temp2=}")
+
+    # first_temp3: Celsius | None = get_first_temp_generic(
+    #     [Fareng(-40.0), Fareng(5.1), Fareng(36.0)]
+    # )
+    # print(f"{first_temp3=}")
+
+
+if __name__ == "__main__":
+    print(f"{TYPE_CHECKING=}")
+
+    run_get_user_data()
+    print("\n------------\n")
+
+    run_convert_c_to_f()
+    print("\n------------\n")
+
+    run_generic()
+    print("\n------------\n")