[moonchild]

Looks like classes can't be closures, though:

  >>> def f():
  ...     x = 5
  ...     class Blub:
  ...             def incx(self):
  ...                     x += 1
  ...             def getx(self):
  ...                     return x
  ...     return Blub()
  ... 
  >>> j = f()
  >>> j.incx()
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "<stdin>", line 5, in incx
  UnboundLocalError: local variable 'x' referenced before assignment

[cessor]

When using it like this, the interpreter opens a new namespace where the variables are bound. The x is declared in the outer scope, so it can't find it. However, you can ask python to keep searching vor the name `x` in the closest outer scope, that is what the `nonlocal` statement is for:

    def f():
        x = 5
        class Blub:
            def incx(self):
                nonlocal x
                x += 1

            def getx(self):
                return x

        return Blub()

    j = f()
    j.incx()
    print(j.getx())

This will print 6, as expected.