在python中的类函数中更改全局变量

Question

I've seen questions asked on this before, but I'm not able to recreate the alteration of global variables within a class function:

test = 0
class Testing:
    def add_one():
        global test
        test += 1

when I type in

Testing.add_one
print (test)

It prints "0". How do I get the function in the class to add one to test?

Thank you!

Answer 1

You are not calling the function add_one

test = 0    
class Testing:
    def add_one():
        global test
        test += 1
Testing.add_one()
print (test)

Answer 2

You didn't call the function. And if you did you will get a TypeError

It should be like this

test = 0
class Testing(object):
    @staticmethod
    def add_one():
        global test
        test += 1

Testing.add_one()

Answer 3

try this,

test = 0
class Testing:
    def add_one(self):
        global test
        test += 1
        print(test)

t = Testing()
t.add_one()

Answer 4

You should call the method. Then only it will increment the value of the variable test .

In [7]: test = 0
   ...: class Testing:
   ...:     def add_one():
   ...:         global test
   ...:         test += 1                                                                                                                                                                

# check value before calling the method `add_one`
In [8]: test
Out[8]: 0

# this does nothing
In [9]: Testing.add_one
Out[9]: <function __main__.Testing.add_one()>

# `test` still holds the value 0
In [10]: test
Out[10]: 0

# correct way to increment the value
In [11]: Testing.add_one()

# now, check the value
In [12]: test
Out[12]: 1