Restrict internal use method call

Let's say I have a class Task

and another class Subtask

that is delegated to perform a specific task, but always in the execution context Task

. This means it Subtask

always accepts Task

and performs actions on attributes Tasks

:

class Task:
    pass

class Subtask:
    def __init__(self, task):
        self.task = task

    def run(self):
        # performs actions on self.task own attributes

      

        
        
        
      

    

Then we have a method in Task

that does a specific update. This method is intended to be used for internal use only:

class Task:
    def _update(self):
        # do something restricted

      

        
        
        
      

    

But then we really want to call this method from within Subtask

to perform these updates:

class Subtask:
    def run(self):
        # do stuff
        self.task._update()

      

        
        
        
      

    

Here's the problem: this is wrong behavior. The internal use method should not be called from any other context and the IDE gives the appropriate warning as expected.

However, I do not want this method to be publicly available Task.update()

because it is still of limited use. We just want to do something like friendship like in C ++.

We want to keep this method Task._update()

private, but we give the class a Subclass

special permission.

Is there a way to do this?

PS: I know how Python works, I know I can just use this method externally and ignore this warning or make it public and just not use it elsewhere to summarize: be responsible , as the Python motto proclaims. I agree with this, but I also wonder if there is any way to achieve what I need in a way that makes sense with Python philosophy.