Python函数如何用参数类型检查确保数据安全 Python函数参数类型校验的入门技巧​

def add(x: int, y: int) -> int:
    return x + y

print(add(1, 2))  # 输出 3
print(add("1", "2"))  # 运行时不会报错，但MyPy会警告

x: int

y: int

x

y

-> int

mypy your_file.py

add("1", "2")

def process_data(data):
    if not isinstance(data, list):
        raise TypeError("Data must be a list")
    for item in data:
        if not isinstance(item, int):
            raise TypeError("All items in the list must be integers")
    # 在这里处理数据
    print("Data is valid:", data)

process_data([1, 2, 3]) # 输出 Data is valid: [1, 2, 3]
process_data([1, "2", 3]) # 抛出 TypeError: All items in the list must be integers
process_data(123) # 抛出 TypeError: Data must be a list

data

TypeError

def calculate_average(numbers: list[int]) -> float:
    if not isinstance(numbers, list):
        raise TypeError("Input must be a list")
    if not all(isinstance(x, (int, float)) for x in numbers):
        raise TypeError("All elements in the list must be numbers")
    if not numbers:
        return 0.0  # 避免除以零
    return sum(numbers) / len(numbers)

print(calculate_average([1, 2, 3, 4, 5])) # 输出 3.0
print(calculate_average([1, 2, "3", 4, 5])) # 抛出 TypeError: All elements in the list must be numbers

numbers: list[int]

class Dog:
    def __init__(self, name: str, age: int):
        self.name = name
        self.age = age

def greet_dog(dog: Dog):
    if not isinstance(dog, Dog):
        raise TypeError("Input must be a Dog object")
    print(f"Woof! My name is {dog.name} and I am {dog.age} years old.")

my_dog = Dog("Buddy", 3)
greet_dog(my_dog) # 输出 Woof! My name is Buddy and I am 3 years old.

greet_dog("Buddy") # 抛出 TypeError: Input must be a Dog object

greet_dog

isinstance(dog, Dog)

from typing import Union

def process_value(value: Union[int, str]):
    if isinstance(value, int):
        print("Processing integer:", value * 2)
    elif isinstance(value, str):
        print("Processing string:", value.upper())
    else:
        raise TypeError("Value must be an integer or a string")

process_value(10) # 输出 Processing integer: 20
process_value("hello") # 输出 Processing string: HELLO
process_value(10.5) # 抛出 TypeError: Value must be an integer or a string

value: Union[int, str]

typing

Optional

List

Dict

attrs

from pydantic import BaseModel, ValidationError

class User(BaseModel):
    id: int
    name: str
    signup_ts: Optional[datetime] = None
    friends: List[int] = []

try:
    user = User(id='123', name='John Doe')
except ValidationError as e:
    print(e)
# 输出
# 1 validation error for User
# id
#   value is not a valid integer (type=type_error.integer)

id

ValidationError