将全局值作为参数传递给装饰器和函数

Question

我是 python 的新手，正在学习装饰器。没有参数和带有参数（作为字符串）的装饰器似乎很简单。但是，如果我想传递一个全局值而不是 'srting' 作为参数，它就会失败。我有所有这些不同的文件，所以我想使用全局变量。

File1:
def decorator(arg1, arg2):
    def real_decorator(function):
        def wrapper(*args):
            print "i am decorated"
            print arg1, arg2
            function(*args)
        return wrapper
    return real_decorator

File2:
def glob(a, b):
    global arg1
    arg1 = a
    global arg2
    arg2 = b

@decorator(arg1, arg2) # pass it as 'string' ie('arg1', 'arg2') it PASSES, pass it as i have showed, it FAILS
def print_args(*args):
    print 'i am ordinary'
    for arg in args:
        print arg

File3:
#calling functions
glob(1, 2)
print_args(3,4,5)
======================================
Pass: (when given as string)
i am decorated
arg1 arg2
i am ordinary
3
4
5
======================================
Fail: (when given global var)
Traceback (most recent call last):
 File "/User/File2.py", line 19, in <module>
@decorator(arg1, arg2)
NameError: global name 'arg1' is not defined

非常感谢您对此的任何帮助。从昨天开始我就被这个问题困住了..!!

Answer 1

您应该在 zero-indentation 级别声明 arg1 和 arg2，即作为模块内的全局变量：

arg1 = None
arg2 = None

def decorator(arg1, arg2):
    def real_decorator(function):
        def wrapper(*args):
            print("i am decorated")
            print(arg1, arg2)
            function(*args)
        return wrapper
    return real_decorator

def glob(a, b):
    global arg1
    arg1 = a
    global arg2
    arg2 = b

glob(1, 2)

#calling functions
@decorator(arg1, arg2) # pass it as 'string' ie('arg1', 'arg2') it PASSES, pass it as i have showed, it FAILS
def print_args(*args):
    print('i am ordinary')
    for arg in args:
        print(arg)


print_args(3,4,5)

此外，确保在传递 arg1 和 arg2 作为装饰器参数之前调用 glob(1, 2)。

将全局值作为参数传递给装饰器和函数

Passing a global value as argument to a decorator and the function

python

arguments

global

decorator