Annotations

Quick tutorial for python annotations check list.

Common types

Basic

numbers.py


# Numbers
int_num: int = 68
float_num: float = 32.2
double_num: double = 320.233
 
# String
name: str = "Peter"
by: bytes = b"test"
is_ok: bool = False

Special

lists.py


# List
num_list: list = []
num_list_specific: list[int] = [1,2,3] ## Python 3.9
 
# Special
mytuple: tuple = ("apple", "banana", "cherry")
mytuple_specific: tuple[int, str, str] = (1, "banana", "cherry") # Python 3.9+
 
mySet: set[int] = {6, 7} ## Python 3.9
myDict: dict[str, int] = { "age" : 30 }
 
whatever: Any = False

:::tip

For Python 3.8 and earlier, you may use the typing collection


from typing import List, Set, Dict, Tuple

:::

Functions

functions.py


def add(a: int, b: int) -> int:
    return a + b
 
def addVoid(a: int, b: int) -> None:
    print( a + b )
 
from typing import Iterator # Python < 3.10+ in case
 
def gen(n: int) -> Iterator[int]:
    i = 0
    while i < n:
        yield i
        i += 1

Special type method

`Literal` types

The Literal is used to define your own output types like enum

literal.py


def isBigger(a: int, b: int) -> Literal["yes", "no"]:
    return "yes" if a > b else "no"

:::tip

For Python 3.8 and earlier, you may use typing collection


from typing import Literal

:::

`type` types

The type is used to define your own type for later used.

typeUsage.py


# Define a type
type Point = tuple[float, float]
 
myPoint: Point = (1.1, 4.7)
 
def makePoint(a: float, b: float) -> Point:
    return (a, b)

`Union` types

The Union is used to define mixed type.

union.py


from typing import Union # Python < 3.10+ in case
 
# Python 3.10+
mix_list: list[str | bool] = ["omg", True, "ok"] 
 
mix_list_union: list[Union[str | bool]] = ["gg", True, "ok"]

`Optional` types

The Optional is used to define optional params in functions.

optional.py


from typing import Optional # Python < 3.10+ in case
 
def isBigger(a: Optional[str] = None) -> None:
    print(a)
 
# Other usage beside Optional
def isBigger(a:  str | None = None) -> None:
    print(a)