[实用装饰器函数]#python

deco_funcs.md

函数运行时间

import time
import functools
from functools import singledispatch

def clock(func):
    @functools.wraps(func)
    def clocked(*args, **kwargs):
        t0 = time.time()
        result = func(*args, **kwargs)
        elapsed = time.time() - t0
        name = func.__name__
        arg_lst = []
        if args:
            arg_lst.append(', '.join(repr(arg) for arg in args))
        if kwargs:
            pairs = ['%s=%r' % (k, w) for k, w in sorted(kwargs.items())]
            arg_lst.append(','.join(pairs))
        arg_str = ','.join(arg_lst)
        print ('[%0.8fs]%s(%s) -> %r' % (elapsed, name, arg_str, result))
        return result
    return clocked

类型检查

# coding: utf8
import collections
import functools
import inspect


def check(func):
    msg = ('Expected type {expected!r} for argument {argument}, '
           'but got type {got!r} with 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())   # 参数名称

    @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解
        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解
        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


@check
def foobar(a: int, b: str, c: float = 3.2) -> tuple:
    return a, b, c