Type Hints in Python
| Type Hint | Meaning | Example(s) |
|---|---|---|
int |
Integer | x: int = 5 |
float |
Floating-point number | pi: float = 3.14 |
str |
String | name: str = "John" |
bool |
Boolean | is_active: bool = True |
list |
List | numbers: list[int] = [1, 2, 3] |
tuple |
Tuple | coordinates: tuple[int, int] = (10, 20) |
dict |
Dictionary (string keys, any values) | person: dict[str, any] = {"name": "John", "age": 30} |
dict |
Dictionary (tuple keys, any values) | person: dict[tuple, any] = {(10,12): "John", (11,12): 30} |
set |
Set | unique_numbers: set[int] = {1, 2, 3} |
any |
any type (dynamic typing) | value: any = 10 |
Union |
Union of multiple types | mixed: Union[int, str] = 10 |
Optional |
Optional type (None or specified type) | age: Optional[int] = None |
Callable |
Callable (function or method) | operation: Callable[[int, int], int] = lambda x, y: x + y |
Iterable |
Iterable (e.g., list, tuple, dictionary keys) | items: Iterable[int] = [1, 2, 3] |
Iterator |
Iterator (e.g., returned by iter() function) | iter_obj: Iterator[int] = iter([1, 2, 3]) |
Generator |
Generator (function returning iterator) | def squares(n: int) -> Generator[int, None, None]: ... |
Type |
Type (class or type object) | cls: Type[MyClass] = MyClass |
ClassVar |
Class variable (shared among instances) | count: ClassVar[int] = 0 |
AnyStr |
Any string type (str or bytes) | data: AnyStr = "abc" |
NoReturn |
Used for functions that never return a value | def my_func() -> NoReturn: ... |
Literal |
Literal value (specific constant value) | status: Literal["success", "failure"] = "success" |
Final |
Final variable (cannot be reassigned) | MAX_SIZE: Final[int] = 100 |
NewType |
Creates a new distinct type (e.g., for validation) | UserId = NewType("UserId", int) |
Published on 23 Apr 2024
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