Getting container/parent object from within python

by

Pass a reference to the Bar object, like so:

class Foo(object):
    def __init__(self):
        self.text = "Hello World"  # has to be created first, so Bar.__init__ can reference it
        self.bar = Bar(self)

class Bar(object):
    def __init__(self, parent):
        self.parent = parent
        self.newText = parent.text

foo = Foo()

Edit: as pointed out by @thomleo, this can cause problems with garbage collection. The suggested solution is laid out at http://eli.thegreenplace.net/2009/06/12/safely-using-destructors-in-python/ and looks like

import weakref

class Foo(object):
    def __init__(self):
        self.text = "Hello World"
        self.bar = Bar(self)

class Bar(object):
    def __init__(self, parent):
        self.parent = weakref.ref(parent)    # <= garbage-collector safe!
        self.newText = parent.text

foo = Foo()

More Related Contents:

  1. How to make an object indestructible even with force deletion?
  2. How to print instances of a class using print()?
  3. How do I call a parent class’s method from a child class in Python?
  4. Saving and loading multiple objects in pickle file?
  5. Getting an instance name inside class __init__() [duplicate]
  6. What is the difference between __init__ and __call__?
  7. Difference between ‘cls’ and ‘self’ in Python classes?
  8. How to create multiple class objects with a loop in python?
  9. How do I correctly setup and teardown for my pytest class with tests?
  10. How can I create an object and add attributes to it?
  11. “Enabling” comparison for classes [duplicate]
  12. Understanding Python super() with __init__() methods [duplicate]
  13. Python function overloading
  14. How to keep track of class instances?
  15. Is it possible to make abstract classes in Python?
  16. Nested classes’ scope?
  17. What is the __dict__.__dict__ attribute of a Python class?
  18. Calling functions from a Tkinter Frame to another
  19. How can I pickle a dynamically created nested class in python?
  20. Does Python have class prototypes (or forward declarations)?
  21. How to properly overload the __add__ method?
  22. What is the purpose of python’s inner classes?
  23. What is the benefit to using a ‘get function’ for a python class? [closed]
  24. How to access (get or set) object attribute given string corresponding to name of that attribute
  25. class method generates “TypeError: … got multiple values for keyword argument …”
  26. Should I use instance or class attributes if there will only be one instance? [closed]
  27. How can I choose a custom string representation for a class itself (not instances of the class)?
  28. Missing 1 required positional argument
  29. How can I dynamically create class methods for a class in python [duplicate]
  30. What is the difference between super() with arguments and without arguments?

Leave a Comment