MarkingKey

Stephen Pair spair at advantive.com
Tue Jun 11 14:24:45 UTC 2002


Another technique used in Smalltalk where you need an object that can't
be confused with a real object in your domain is to simply instantiate a
new object and hold onto it (this works if you don't need it to me
polymorphically compatible with the objects in your domain):

(where Marker is a class var)

MyClass class>>initialize

	Marker := Object new.

MyClass class>>isMarker: anObject

	^anObject == Marker

This object will never be confused with an object in your domain.

- Stephen




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