The visitor design pattern is a way of separating an algorithm from an object structure upon which it operates. This enables the addition of new operations to existing object structures without modifying those structures.

Cobra provides a Vistor base class in its standard library. You can read its doc string and browse its members by looking in CobraLang.cobra online or in your local installation.

See also:

•  http://en.wikipedia.org/wiki/Visitor_pattern
•  http://www.javaworld.com/javaworld/javatips/jw-javatip98.html