python--用装饰器做参数检查

1. 装饰器检测参数

import collections
import functools
import inspect


def para_check(func):
    """
    函数参数检查装饰器，需要配合函数注解表达式（Function Annotations）使用
    """
    msg = 'Argument {argument} must be {expected!r},but got {got!r},value {value!r}'

    # 获取函数定义的参数
    sig = inspect.signature(func)
    parameters = sig.parameters     # 参数有序字典
    arg_keys = tuple(parameters.keys())

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        CheckItem = collections.namedtuple('CheckItem', ('anno', 'arg_name', 'value'))
        check_list = []

        # collect args  *args 传入的参数以及对应的函数参数注释
        for i, value in enumerate(args):
            arg_name = arg_keys[i]
            anno = parameters[arg_name].annotation
            check_list.append(CheckItem(anno, arg_name, value))

        # collect kwargs **kwargs 传入的参数以及对应的函数参数注释
        for arg_name, value in kwargs.items():
            anno = parameters[arg_name].annotation
            check_list.append(CheckItem(anno, arg_name, value))

        # check type
        for item in check_list:
            if not isinstance(item.value, item.anno):
                error = msg.format(expected=item.anno, argument=item.arg_name,
                                   got=type(item.value), value=item.value)
                raise TypeError(error)
        return func(*args, **kwargs)
    return wrapper


@para_check
def test(x: int, y: int):
    return x + y


test('1', 2)

2. 执行结果

C:\Users\HuJun\PycharmProjects\pythonProject\venv\Scripts\python.exe "F:\PyCharm\PyCharm 2021.1.1\plugins\python\helpers\pydev\pydevd.py" --multiproc --qt-support=auto --client 127.0.0.1 --port 3899 --file C:/Users/HuJun/PycharmProjects/pythonProject/daily_tesy/decorate_check.py
Connected to pydev debugger (build 211.7142.13)
Traceback (most recent call last):
  File "F:\PyCharm\PyCharm 2021.1.1\plugins\python\helpers\pydev\pydevd.py", line 1483, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "F:\PyCharm\PyCharm 2021.1.1\plugins\python\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Users/HuJun/PycharmProjects/pythonProject/daily_tesy/decorate_check.py", line 48, in <module>
    test('1', 2)
  File "C:/Users/HuJun/PycharmProjects/pythonProject/daily_tesy/decorate_check.py", line 38, in wrapper
    raise TypeError(error)
TypeError: Argument x must be <class 'int'>,but got <class 'str'>,value '1'
python-BaseException

Process finished with exit code 1