Python 2.7: How can a class created inside another one query a variable of the class creating it?

Question

I know this is wrong, but I don't know why, not how to do it right. I don't want myParent to be myChlid's superclass. I can't really find words to ask what I want to do so I didn't find any way to find an answer online. Maybe you can answer it :)

class myParent():
    def __init__(self, whatever):
        self.child = myChild(parent_ = self)
        self.myVar = whatever

class myChild():
    def __init__(self, parent_):
        self.parent_ = parent_
        print self.parent_.myVar

myParent(whatever)

It raises this error :

# AttributeError: myParent instance has no attribute 'myVar' #

Are you looking for something like this maybe? stackoverflow.com/questions/18006310/… — Zack Tarr
– Zack Tarr, Commented Feb 9, 2018 at 17:12
Looks fine, except that you need to set the member before you can read it. That's just a sequence-of-events problem — greggo
– greggo, Commented Feb 9, 2018 at 17:12

Kevin · Accepted Answer · 2018-02-09 17:12:59Z

1

You can't access myVar from within myChild.__init__ because you're creating the myChild instance before you create the self.myVar attribute. Try switching the order of those lines.

class myParent():
    def __init__(self, whatever):
        self.myVar = whatever
        self.child = myChild(parent_ = self)

answered Feb 9, 2018 at 17:12

Kevin

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