我有一个由装饰器转移变量insurance_mode的问题。我将通过以下装饰器语句来实现:

@execute_complete_reservation(True)
def test_booking_gta_object(self):
    self.test_select_gta_object()

但不幸的是,这种说法并不管用。也许也许有更好的办法来解决这个问题。

def execute_complete_reservation(test_case,insurance_mode):
    def inner_function(self,*args,**kwargs):
        self.test_create_qsf_query()
        test_case(self,*args,**kwargs)
        self.test_select_room_option()
        if insurance_mode:
            self.test_accept_insurance_crosseling()
        else:
            self.test_decline_insurance_crosseling()
        self.test_configure_pax_details()
        self.test_configure_payer_details

    return inner_function

当前回答

它是一个可以以多种方式调用的装饰器(在python3.7中测试):

import functools


def my_decorator(*args_or_func, **decorator_kwargs):

    def _decorator(func):

        @functools.wraps(func)
        def wrapper(*args, **kwargs):

            if not args_or_func or callable(args_or_func[0]):
                # Here you can set default values for positional arguments
                decorator_args = ()
            else:
                decorator_args = args_or_func

            print(
                "Available inside the wrapper:",
                decorator_args, decorator_kwargs
            )

            # ...
            result = func(*args, **kwargs)
            # ...

            return result

        return wrapper

    return _decorator(args_or_func[0]) \
        if args_or_func and callable(args_or_func[0]) else _decorator


@my_decorator
def func_1(arg): print(arg)

func_1("test")
# Available inside the wrapper: () {}
# test


@my_decorator()
def func_2(arg): print(arg)

func_2("test")
# Available inside the wrapper: () {}
# test


@my_decorator("any arg")
def func_3(arg): print(arg)

func_3("test")
# Available inside the wrapper: ('any arg',) {}
# test


@my_decorator("arg_1", 2, [3, 4, 5], kwarg_1=1, kwarg_2="2")
def func_4(arg): print(arg)

func_4("test")
# Available inside the wrapper: ('arg_1', 2, [3, 4, 5]) {'kwarg_1': 1, 'kwarg_2': '2'}
# test

PS感谢用户@norok2 - https://stackoverflow.com/a/57268935/5353484

UPD装饰器,用于根据注释验证类的函数和方法的参数和/或结果。可用于同步或异步版本:https://github.com/EvgeniyBurdin/valdec

其他回答

匿名设置中的参数装饰。

在许多可能的“嵌套”语法糖装饰的两种变化中被提出。它们之间的区别在于执行wrt到目标函数的顺序,并且它们的效果通常是独立的(不相互作用)。

装饰器允许在目标函数执行之前或之后“注入”自定义函数。

这两个函数的调用都发生在一个元组中。默认情况下,返回值是目标函数的结果。

语法糖装饰@first_internal(send_msg)('…end')要求版本>= 3.9,请参阅PEP 614放松对装饰器的语法限制。

functools使用。以保留目标函数的文档字符串。

from functools import wraps


def first_external(f_external):
    return lambda *args_external, **kwargs_external:\
           lambda f_target: wraps(f_target)(
               lambda *args_target, **kwargs_target:
                  (f_external(*args_external, **kwargs_external),
                   f_target(*args_target, **kwargs_target))[1]
           )


def first_internal(f_external):
    return lambda *args_external, **kwargs_external:\
           lambda f_target: wraps(f_target)(
               lambda *args_target, **kwargs_target:
                  (f_target(*args_target, **kwargs_target),
                   f_external(*args_external, **kwargs_external))[0]
           )


def send_msg(x):
   print('msg>', x)


@first_internal(send_msg)('...end')    # python >= 3.9
@first_external(send_msg)("start...")  # python >= 3.9
def test_function(x):
    """Test function"""
    print('from test_function')
    return x


test_function(2)

输出

msg> start...
from test_function
msg> ...end

讲话

composition decorators, such as pull-back and push-forward (maybe in a more Computer Science terminology: co- and resp. contra-variant decorator), could more useful but need ad-hoc care, for example composition rules, check which parameters go where, etc syntactic sugar acts as a kind of partial of the target function: once decorated there is no way back (without extra imports) but it is not mandatory, a decorator can be used also in its extended forms, i.e. first_external(send_msg)("start...")(test_function)(2) the results of a workbench with timeit.repeat(..., repeat=5, number=10000) which compare the classical def and lambda decoration shows that are almost equivalent: for lambda: [6.200810984999862, 6.035239247000391, 5.346362481000142, 5.987880147000396, 5.5331550319997405] - mean -> 5.8206 for def: [6.165001932999985, 5.554595884999799, 5.798066574999666, 5.678178028000275, 5.446507932999793] - mean -> 5.7284 naturally an non-anonymous counterpart is possible and provides more flexibility

我想展示一个想法,在我看来很优雅。t.dubrownik提出的解决方案显示了一个始终相同的模式:无论装饰器做什么,您都需要三层包装器。

所以我认为这是一个元装饰师的工作,也就是说,装饰师的装饰师。由于decorator是一个函数,它实际上是一个带有参数的常规decorator:

def parametrized(dec):
    def layer(*args, **kwargs):
        def repl(f):
            return dec(f, *args, **kwargs)
        return repl
    return layer

这可以应用于常规的装饰器,以便添加参数。例如,我们有一个decorator,它将一个函数的结果加倍:

def double(f):
    def aux(*xs, **kws):
        return 2 * f(*xs, **kws)
    return aux

@double
def function(a):
    return 10 + a

print function(3)    # Prints 26, namely 2 * (10 + 3)

使用@ parameterized,我们可以构建一个带参数的通用@multiply装饰器

@parametrized
def multiply(f, n):
    def aux(*xs, **kws):
        return n * f(*xs, **kws)
    return aux

@multiply(2)
def function(a):
    return 10 + a

print function(3)    # Prints 26

@multiply(3)
def function_again(a):
    return 10 + a

print function(3)          # Keeps printing 26
print function_again(3)    # Prints 39, namely 3 * (10 + 3)

通常,参数化装饰器的第一个参数是函数,而其余参数将对应于参数化装饰器的参数。

一个有趣的用法示例可以是类型安全的断言装饰器:

import itertools as it

@parametrized
def types(f, *types):
    def rep(*args):
        for a, t, n in zip(args, types, it.count()):
            if type(a) is not t:
                raise TypeError('Value %d has not type %s. %s instead' %
                    (n, t, type(a))
                )
        return f(*args)
    return rep

@types(str, int)  # arg1 is str, arg2 is int
def string_multiply(text, times):
    return text * times

print(string_multiply('hello', 3))    # Prints hellohellohello
print(string_multiply(3, 3))          # Fails miserably with TypeError

最后注意:这里我没有使用functools。包装器函数,但我建议始终使用它。

以下是对t.dubrownik的回答稍加修改的版本。为什么?

作为通用模板,您应该返回原始函数的返回值。 这将改变函数的名称,这可能会影响其他装饰器/代码。

所以使用@functools.wraps():

from functools import wraps

def create_decorator(argument):
    def decorator(function):
        @wraps(function)
        def wrapper(*args, **kwargs):
            funny_stuff()
            something_with_argument(argument)
            retval = function(*args, **kwargs)
            more_funny_stuff()
            return retval
        return wrapper
    return decorator

上面的回答很棒。这个例子还演示了@wraps,它从原始函数中获取文档字符串和函数名,并将其应用于新的包装版本:

from functools import wraps

def decorator_func_with_args(arg1, arg2):
    def decorator(f):
        @wraps(f)
        def wrapper(*args, **kwargs):
            print("Before orginal function with decorator args:", arg1, arg2)
            result = f(*args, **kwargs)
            print("Ran after the orginal function")
            return result
        return wrapper
    return decorator

@decorator_func_with_args("foo", "bar")
def hello(name):
    """A function which prints a greeting to the name provided.
    """
    print('hello ', name)
    return 42

print("Starting script..")
x = hello('Bob')
print("The value of x is:", x)
print("The wrapped functions docstring is:", hello.__doc__)
print("The wrapped functions name is:", hello.__name__)

打印:

Starting script..
Before orginal function with decorator args: foo bar
hello  Bob
Ran after the orginal function
The value of x is: 42
The wrapped functions docstring is: A function which prints a greeting to the name provided.
The wrapped functions name is: hello

下面是一个使用带有参数的装饰器的Flask示例。假设我们有一个路由'/user/name',我们想要映射到他的主页。

def matchR(dirPath):
    def decorator(func):
        def wrapper(msg):
            if dirPath[0:6] == '/user/':
                print(f"User route '{dirPath}' match, calling func {func}")
                name = dirPath[6:]
                return func(msg2=name, msg3=msg)
            else:
                print(f"Input dirPath '{dirPath}' does not match route '/user/'")
                return
        return  wrapper
    return decorator

#@matchR('/Morgan_Hills')
@matchR('/user/Morgan_Hills')
def home(**kwMsgs):
    for arg in kwMsgs:
        if arg == 'msg2':
            print(f"In home({arg}): Hello {kwMsgs[arg]}, welcome home!")
        if arg == 'msg3':
            print(f"In home({arg}): {kwMsgs[arg]}")

home('This is your profile rendered as in index.html.')

输出:

User route '/user/Morgan_Hills' match, calling func <function home at 0x000001DD5FDCD310>
In home(msg2): Hello Morgan_Hills, welcome home!
In home(msg3): This is your profile rendered as in index.html.