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2: Variables, Objects and Attributes
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Summary
----------
- An object is a collection of attributes
- variables reference objects, which have a lifetime of their own independent of any variable referencing them
- An object can be referenced by many variables and so has no fixed and immutable name.
- An attribute is a reference to an object

Pythons approach
-----------------
- Names are just variables that store references
- A variable is created by simply using it
- variables are dynamic, untyped and are references to objects

Creating Objects
------------------

.. code-block:: python

    class MyObject:
        myAttribute = 1
    

    #access using dot notation

    print(MyObject.myAttribute) # prints 1
    MyObject.myAttribute = 2
    print(MyObject.myAttribute) # prints 2

    # add an attribute
    MyObject.myNewAttr = 7

    # del an attribute
    del MyObject.myNewAttr


Nested Objects
----------------

.. code-block:: python

    class MyObject1:
        myAttribute1 = 1
        class MyObject2:
            myAttribute2 = 2

    #access
    MyObject1.MyObject2.myAttribute2

    #use a variable to store the reference
    myRef = MyObject1.MyObject2
    myRef.myAttribute2

Modules
------------------------

.. code-block:: python

    import myModule.MyObject # imports just the object
    import myModule.MyObject as MySecondObj #imports the same object but changes the variable that references it 

Namespaces
-------------
- Every object has a __dict__ attribute that is its local namespace
- It records all the objects attributes
- Internally an attribute is looked up in the object dictionary so:

.. code-block:: python

    print(MyObject.myAttribute)

    # is equal to:

    print(MyObject.__dict__["myAttribute"])