Status: IN
The Visitor pattern inverts the standard OCP extension axis: while typical OCP keeps operations closed and allows new types (add subclasses without modifying existing code), Visitor keeps the type hierarchy closed and allows new operations (add visitors without modifying elements) — making it the dual of conventional OCP and suitable precisely when operation volatility exceeds structural volatility.
Visitor's open-ops/closed-structure stance is the precise mirror of OCP's open-structure/closed-ops stance
Depends on (SL): visitor-enables-open-ended-operations, visitor-tradeoff-stable-structure-required, ocp-open-for-extension-closed-for-modification