python 类型提示

python 类型提示

它允许开发者在代码中显式地声明变量、函数、方法等的类型信息。这种类型声明不会影响 Python 解释器的运行，它可以帮助开发人员在编写代码时更好地理解代码中的数据类型，从而提高代码的可读性和可维护性。

基本类型

# 直接定义
age: int = 1
# 声明后定义
num: float
num = 2.0
name:str = "beike"
 
def printname(name: str) -> str:
    return f"Hello, {name}!"
 
def is_even(x: int) -> bool:
    return x % 2 == 0
 
res=printname(name)
print(res)

嵌套类型

使用标准库 typing 标记复合类型

from typing import List, Tuple, Dict, Set
 

my_list: List[int] = [1, 2, 3, 4]

my_tuple: Tuple[int, str, bool] = (1, "hello", True)

my_dict: Dict[str, int] = {"apple": 1, "banana": 2, "orange": 3}

my_set: Set[float] = {1.0, 2.0, 3.0}

复合类型

Union类型用于表示多种类型中的一种，Optional类型用于表示可选类型，Sequence 序列类型

from typing import Union
 
def func(x: Union[int, str]) -> None:
    pass

from typing import Optional, Union
 
def func(x: Optional[Union[int, str]]) -> None:
    pass

Sequence 类型的对象是可以被索引的任何东西：列表、元组、字符串、对象列表、元组列表的元组等。
def test(a: Sequence):
    print(a[0])
    ...

Generator-Iterator

from typing import Generator
 
def even_numbers(n: int) -> Generator[int, None, None]:
    for i in range(n):
        if i % 2 == 0:
            yield i

from typing import Iterator
 
class MyIterator:
    def __init__(self):
        self.current: int = 0
        self.max: int = 5
 
    def __iter__(self) -> Iterator[int]:
        return self
 
    def __next__(self) -> int:
        if self.current >= self.max:
            raise StopIteration
        else:
            self.current += 1
            return self.current

Callable

from typing import Callable
 
def apply(func: Callable[[int, int], int], a: int, b: int) -> int:
    return func(a, b)
 
def add(a: int, b: int) -> int:
    return a + b
 
result = apply(add, 3, 4)
print(result) # 输出7

自定义类型

class Person:
    def __init__(self, name: str, age: int):
        self.name = name
        self.age = age
 
def say_hello(person: Person) -> str:
    return f"Hello, {person.name}!"

其他类型NamedTuple

from typing import NamedTuple
from collections import namedtuple


Employee = namedtuple('Employee',  ["x","y"])

em = Employee(x=1, y='x')
print(em.x,em.y)


Point = NamedTuple('Point', [('x', int),
                             ('y', str)])

p = Point(x=1, y='x')
print(p.x,p.y)

参考博客

https://www.cnblogs.com/luohenyueji/p/17387538.html