全局变量仍然存在我得到“UnboundLocalError：赋值前引用的局部变量'a'”

Question

The following python code gives an error. Why isn't it referencing the global variable a?

a = 10

def b(x):
    if(x == True):
        a = 2
    return a

print(b(False))

The error:

Traceback (most recent call last):
  File "<string>", line 8, in <module>
File "<string>", line 6, in b
UnboundLocalError: local variable 'a' referenced before assignment
> 

Answer 1

The issue is that you're using a local variable that has the same name of the global one. This can help: Modifying global variable with same name as local variable

Edit: in fact, this seems to be working:

a = 10

def b(x):
    if(x == True):
        globals()['a'] = 2
    return a

print(b(False))