type CustomFeatureValue

source code

object --+
         |
        CustomFeatureValue

An abstract base class for base values that define a custom unification method. A CustomFeatureValue's custom unification method will be used during feature structure unification if:

• The CustomFeatureValue is unified with another base value.
• The CustomFeatureValue is not the value of a customized Feature (which defines its own unification method).

If two CustomFeatureValue objects are unified with one another during feature structure unification, then the unified base values they return must be equal; otherwise, an AssertionError will be raised.

Subclasses must define unify() and __cmp__(). Subclasses may also wish to define __hash__().