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

在这里,我们用两个不同的名称和两个不同的年龄运行了两次display info。 现在,每当我们运行display info时,我们的装饰器还添加了打印换行函数前后一行的功能。

def decorator_function(original_function):
    def wrapper_function(*args, **kwargs):
        print('Executed Before', original_function.__name__)
        result = original_function(*args, **kwargs)
        print('Executed After', original_function.__name__, '\n')
        return result
    return wrapper_function


@decorator_function
def display_info(name, age):
    print('display_info ran with arguments ({}, {})'.format(name, age))


display_info('Mr Bean', 66)
display_info('MC Jordan', 57)

输出:

Executed Before display_info
display_info ran with arguments (Mr Bean, 66)
Executed After display_info 

Executed Before display_info
display_info ran with arguments (MC Jordan, 57)
Executed After display_info 

现在让我们继续让decorator函数接受参数。 例如,假设我想为包装器中的所有这些打印语句添加一个可定制的前缀。 现在这将是一个很好的候选参数的装饰。 我们传入的参数就是那个前缀。现在为了做到这一点,我们将添加另一个外层到我们的装饰器中,我将把这个函数称为前缀装饰器。

def prefix_decorator(prefix):
    def decorator_function(original_function):
        def wrapper_function(*args, **kwargs):
            print(prefix, 'Executed Before', original_function.__name__)
            result = original_function(*args, **kwargs)
            print(prefix, 'Executed After', original_function.__name__, '\n')
            return result
        return wrapper_function
    return decorator_function


@prefix_decorator('LOG:')
def display_info(name, age):
    print('display_info ran with arguments ({}, {})'.format(name, age))


display_info('Mr Bean', 66)
display_info('MC Jordan', 57)

输出:

LOG: Executed Before display_info
display_info ran with arguments (Mr Bean, 66)
LOG: Executed After display_info 

LOG: Executed Before display_info
display_info ran with arguments (MC Jordan, 57)
LOG: Executed After display_info 

现在我们在包装器函数的print语句之前有了LOG:前缀,你可以随时更改它。

其他回答

在我的实例中,我决定通过一行lambda来解决这个问题,以创建一个新的decorator函数:

def finished_message(function, message="Finished!"):

    def wrapper(*args, **kwargs):
        output = function(*args,**kwargs)
        print(message)
        return output

    return wrapper

@finished_message
def func():
    pass

my_finished_message = lambda f: finished_message(f, "All Done!")

@my_finished_message
def my_func():
    pass

if __name__ == '__main__':
    func()
    my_func()

执行时,输出:

Finished!
All Done!

也许不像其他解决方案那样可扩展,但对我来说是可行的。

就这么简单

def real_decorator(any_number_of_arguments):
   def pseudo_decorator(function_to_be_decorated):

       def real_wrapper(function_arguments):
           print(function_arguments)
           result = function_to_be_decorated(any_number_of_arguments)
           return result

       return real_wrapper
   return pseudo_decorator

Now

@real_decorator(any_number_of_arguments)
def some_function(function_arguments):
        return "Any"

例如,我在下面创建了multiply(),它可以接受一个参数或不接受参数,也可以不接受装饰器的括号,我在下面创建了sum():

from numbers import Number

def multiply(num=1):
    def _multiply(func):
        def core(*args, **kwargs):
            result = func(*args, **kwargs)
            if isinstance(num, Number):
                return result * num
            else:
                return result
        return core
    if callable(num):
        return _multiply(num)
    else:
        return _multiply

def sum(num1, num2):
    return num1 + num2

现在,我把@multiply(5)放在sum()上,然后调用sum(4,6),如下所示:

# (4 + 6) x 5 = 50

@multiply(5) # Here
def sum(num1, num2):
    return num1 + num2

result = sum(4, 6)
print(result)

那么,我可以得到如下结果:

50

接下来,我把@multiply()放在sum()上,然后调用sum(4,6),如下所示:

# (4 + 6) x 1 = 10

@multiply() # Here
def sum(num1, num2):
    return num1 + num2
    
result = sum(4, 6)
print(result)

或者,我把@multiply放在sum()上,然后调用sum(4,6),如下所示:

# 4 + 6 = 10

@multiply # Here
def sum(num1, num2):
    return num1 + num2
    
result = sum(4, 6)
print(result)

那么,我可以得到如下结果:

10

这是一个函数装饰器模板,如果没有参数,则不需要(),并且支持位置参数和关键字参数(但需要检查locals(),以确定第一个参数是否是要装饰的函数):

import functools


def decorator(x_or_func=None, *decorator_args, **decorator_kws):
    def _decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kws):
            if 'x_or_func' not in locals() \
                    or callable(x_or_func) \
                    or x_or_func is None:
                x = ...  # <-- default `x` value
            else:
                x = x_or_func
            return func(*args, **kws)

        return wrapper

    return _decorator(x_or_func) if callable(x_or_func) else _decorator

下面是一个例子:

def multiplying(factor_or_func=None):
    def _decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            if 'factor_or_func' not in locals() \
                    or callable(factor_or_func) \
                    or factor_or_func is None:
                factor = 1
            else:
                factor = factor_or_func
            return factor * func(*args, **kwargs)
        return wrapper
    return _decorator(factor_or_func) if callable(factor_or_func) else _decorator


@multiplying
def summing(x): return sum(x)

print(summing(range(10)))
# 45


@multiplying()
def summing(x): return sum(x)

print(summing(range(10)))
# 45


@multiplying(10)
def summing(x): return sum(x)

print(summing(range(10)))
# 450

或者,如果不需要位置参数,可以不检查wrapper()中的第一个参数(从而不需要使用locals()):

import functools


def decorator(func_=None, **decorator_kws):
    def _decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kws):
            return func(*args, **kws)
        return wrapper

    if callable(func_):
        return _decorator(func_)
    elif func_ is None:
        return _decorator
    else:
        raise RuntimeWarning("Positional arguments are not supported.")

下面是一个例子:

import functools


def multiplying(func_=None, factor=1):
    def _decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            return factor * func(*args, **kwargs)
        return wrapper

    if callable(func_):
        return _decorator(func_)
    elif func_ is None:
        return _decorator
    else:
        raise RuntimeWarning("Positional arguments are not supported.")


@multiplying
def summing(x): return sum(x)

print(summing(range(10)))
# 45


@multiplying()
def summing(x): return sum(x)

print(summing(range(10)))
# 45


@multiplying(factor=10)
def summing(x): return sum(x)

print(summing(range(10)))
# 450


@multiplying(10)
def summing(x): return sum(x)
print(summing(range(10)))
# RuntimeWarning Traceback (most recent call last)
#    ....
# RuntimeWarning: Positional arguments are not supported.

(部分改编自@ShitalShah的回答)

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.