All explanations can be found in Python Documentation The Python Tutorial
For your first error <type 'exceptions.NameError'>: name 'outer_var' is not defined
. The explanation is:
There is no shorthand for referencing data attributes (or other methods!) from within methods. I find that this actually increases the readability of methods: there is no chance of confusing local variables and instance variables when glancing through a method.
quoted from The Python Tutorial 9.4
For your second error <type 'exceptions.NameError'>: name 'OuterClass' is not defined
When a class definition is left normally (via the end), a class object is created.
quoted from The Python Tutorial 9.3.1
So when you try inner_var = Outerclass.outer_var
, the Quterclass
hasn't been created yet, that's why name 'OuterClass' is not defined
A more detailed but tedious explanation for your first error:
Although classes have access to enclosing functions’ scopes, though, they do not act as enclosing scopes to code nested within the class: Python searches enclosing functions for referenced names, but never any enclosing classes. That is, a class is a local scope and has access to enclosing local scopes, but it does not serve as an enclosing local scope to further nested code.
quoted from Learning.Python(5th).Mark.Lutz