全局函数，从不同文件调用的变量

Question

I have 2 different files: One is from CI build: build.py

ABC_ACTIVATE = False
def activate_abc():
    global ABC_ACTIVATE
    ABC_ACTIVATE = True
    # Maybe some more very long code.

One is from customize customize.py

from build import *

activate_abc()
print ABC_ACTIVATE

The idea is customize the activation for each environment by 1 function instead of very long code. But it doesn't work since ABC_ACTIVATE is always False .

It seems that the global variable cannot receive the same context in the other file. Potentially some "cyclical dependencies" problem.

So my question is: Is there any better structure solution? The idea is still activate by a function and customize.py would be the last setting for apache build.

Answer 1

The global seem cannot receive the same context in the other files. Maybe some "cyclical dependencies" problem.

Once you imported it, ABC_ACTIVATE becomes local in the context of that script. Therefore, mutating the variable in build.py won't reflect in your other module.

So my question is: Is there any better structure solution?

One thing you could is create an intermediary method that return the ABC_ACTIVATE Boolean in your build.py .

def is_abc_activated():
    return ABC_ACTIVATE

and then importing it like so,

from build import activate_abc, is_abc_activated

print(is_abc_activated())
activate_abc()
print(is_abc_activated())

>>>>
False
True

---

Basically, this will remove your unconditional import from build import * which is an anti-idiom in Python. Also, it will increase readability since accessing ABC_ACTIVATE can be confusing on what exactly you're doing.

Answer 2

After some discussion, my friend found a quite hack solution for it:

build.py:

ABC_ACTIVATE = False
def activate_abc(other_context):
    other_context.ABC_ACTIVATE = True

And in customize.py:

from build import *
activate_abc(sys.modules[__name__])
print ABC_ACTIVATE

It works now.

Answer 3

That looks like incorrect syntax for a function definition in build.py: the first { should be a : and the second } is not needed as python uses indentation to signify code blocks

ACTIVATE = False
def activate():
    global ACTIVATE
    ACTIVATE = True

Maybe you could also do...

import build
build.activate() 

...As when the script in build.py uses the variable in the same file whereas your imported variable is a different variable since its being imported to the current file's namespace.