3 ms·

Zahns Construct

• immibis 2y ago
  It seems like a complicated way to pretend you are not using goto while having semantics identical to goto. One advantage is that it is a block scope so if e.g. C++ had this, destructors could run, but this could also be supported with goto.
  • 082349872349872 2y ago
    The semantics are much more restricted than goto. (a goto could always create a loop but situation indicators don't; a goto can jump between binding contours but situation indicators don't; etc.) I think of it as an imperative way to pretend you're writing a tail-recursive nest with multiple base cases.
  • Joker_vD 2y ago
    Does the following also have "semantics identical to goto"? // functional lands data EC = Situation1 | ... | SituationN case (Expr0) of Situation1 -> IOAction1 ... SituationN -> IOActionN // imperative lands type Outcome int const Situation1 Outcome = iota, Situation2, ... SituationN var outcome Outcome for { ... { outcome = Situation1; break } ... { outcome = SituationN; break } } switch outcome { case Situation1: <statements1> ... case SituationN: <statementsN> } I personally don't think so, Zahn's construct is merely a way to succinctly express such a switch in the control flow. In fact, Rust almost has it, with its loops being expressions.
    • immibis 2y ago
      Yes? This is making the code worse in order to dogmatically avoid goto.