在 Python 中输入对象命名空间

Question

Is there a way to enter an object's namespace so that I can use its methods as though they were global? I was thinking of something using the with statement.

class Bar():
    
    def methodA(self):
        # do stuff

    def methodB(self):
        # do more stuff

    def __enter__(self):
        # somehow enter object namespace / transfer methods into global namespace

    def __exit__(self, *args):
        # exit object namespace / get rid of globalized methods

foo = Bar()

with foo:
    methodA() # all works fine
    methodB()

methodA() # throws an error

This is just a thought, that might not work at all. Or maybe there's a solution without the with statement.

Answer 1

This answers the original question but I suggest don't use it .

---

Similar to the suggested way of wKavey .

But I'm not sure why I would want to do that. I would need to make sure that there is no variable methodA in the global namespace.

class Bar():
    
    def __init__(self, value=5):
        self.value = value
        
    def methodA(self):
        return self.value

    def methodB(self):
        return -self.value

    def __enter__(self):
        global methodA
        global methodB
        methodA = self.methodA
        methodB = self.methodB

    def __exit__(self, *args):
        global methodA
        del methodA
        global methodB
        del methodB
        pass

foo = Bar()

with foo:
    print(methodA()) # all works fine
    print(methodB())

methodA() # throws an error

Answer 2

You can probably use the techniques described here: Insert variable into global namespace from within a function?

I'd imagine it will require some bookkeeping in the __enter__ and __exit__ functions in order to clean up after itself. This isn't really something standard, so there my be some other foot-guns that I'm overlooking.

Answer 3

(oh. Maximilian Peters' answer is doing the same with slightly different syntax and was here first...)

nothing i'd recommend but you could do this (you get in trouble of course if there is already a methodA in the global namespace):

class Bar():

    def methodA(self):
        print("methodA called")

    def methodB(self):
        print("methodB called")

    def __enter__(self):
        g = globals()
        g["methodA"] = self.methodA
        g["methodB"] = self.methodB

    def __exit__(self, *args):
        g = globals()
        del g["methodA"]
        del g["methodB"]

foo = Bar()

with foo:
    methodA()  # all works fine
    methodB()