Status: OUT
Visitor's maximally unconstrained operation extension — requiring neither common parent class nor specific structural substrate — achieves full applicability only while element classes expose sufficient internal state through their public interfaces to support meaningful visitor operations.
Visitor's structural universality is operationally bounded by its demand that elements expose internal state
Depends on (SL): gof-visitor-no-common-parent-required, visitor-traverses-any-object-structure
Unless: gof-visitor-breaks-encapsulation