Calling an instance variable from a class that is inside of that class

Question

I have a class that has a logger instance variable, and I am creating another class inside of that and I want to use the logger instance variable inside of that class, but not sure how to call it.

Example Code:

class A():
    def __init__(self):
        self.logger = Logger.get() #this works fine didn't include the Logger class

    def func(self):
        class B():
            def __init__(self):
                self.a = 'hello'
            def log(self):
            #How do I call A's logger to log B's self.a
            #I tried self.logger, but that looks inside of the B Class

unutbu · Accepted Answer · 2013-07-22 20:56:28Z

7

As the Zen of Python states, "Flat is better than nested." You could un-nest B, and pass the logger as an argument to B.__init__. By doing so,

You make clear what variables B depends on.
B becomes easier to unit test
B may be reused in other situations.

class A():
    def __init__(self):
        self.logger = Logger.get() #this works fine didn't include the Logger class

    def log(self):
        b = B(self.logger)

class B():
    def __init__(self, logger):  # pass the logger when instantiating B
        self.a = 'hello'

answered Jul 22, 2013 at 20:56

unutbu

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Comments

John Kugelman · Accepted Answer · 2013-07-22 20:46:15Z

5

The name self isn't a language requirement, it's merely a convention. You can use a different variable name like a_self so the outer variable isn't masked.

class A():
    def __init__(self):
        self.logger = Logger.get() #this works fine didn't include the Logger class

    def func(a_self):
        class B():
            def __init__(self):
                self.a = 'hello'
            def log(self):
                a_self.logger.log('...')

answered Jul 22, 2013 at 20:46

John Kugelman

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