I'm exploring the exception support in VM, and found two strange primitives used by BlockClosure, which simply fail and doing nothing. primitiveMarkUnwindMethod "Primitive. Mark the method for exception unwinding. The primitive must fail after marking the context so that the regular code is run." self inline: false. ^self primitiveFail primitiveMarkHandlerMethod "Primitive. Mark the method for exception handling. The primitive must fail after marking the context so that the regular code is run." self inline: false. ^self primitiveFail Any ideas, why they still in use? Can there be something in between, when interpreter enters the method? Or, if nothing, then why they still there? :) -- Best regards, Igor Stasenko AKA sig.