Class ExtensionNode

Base class for extensions nodes.

A new extension node class should override the _extension_name. The concrete node implementations are then derived from this extension node class.

To call an instance method from a parent class you have multiple options:

• use super, but with the normal node class, e.g.:

  >>>  super(mdp.nodes.SFA2Node, self).method()      # doctest: +SKIP

  Here SFA2Node was given instead of the extension node class for the SFA2Node.

  If the extensions node class is used directly (without the extension mechanism) this can cause problems. In that case you have to be careful about the inheritance order and the effect on the MRO.

• call it explicitly using the __func__ attribute [python version < 3]:

  >>> parent_class.method.__func__(self)             # doctest: +SKIP

  or [python version >=3]:

  >>> parent_class.method(self)                      # doctest: +SKIP

To call the original (pre-extension) method in the same class use you simply prefix the method name with '_non_extension_' (this is the value of the ORIGINAL_ATTR_PREFIX constant in this module).

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