3 ms·

I don't agree with this, and I'm personally an anti-OOP militant. Inheritance isn't the root of all evil, dynamic dispatch is. It's a remarkably powerful imple

• bccdee 5y ago
  What enormous cost — slightly slower function calls? That's a pretty minor cost, and dynamic dispatch can be extremely useful sometimes.
  • duped 5y ago
    Enormously slower function calls and zero inlining without advanced dynamic compilation, which has a number of pitfalls.
    • throwaway894345 5y ago
      Devirtualization optimizations can turn semantically "dynamic" dispatches into static dispatches, but sometimes you really just need a dynamic dispatch. Note that a dynamic dispatch doesn't have to be anything more than a branch. Further, sometimes devirtualizing everything leads to enormous binaries and compile times. Runtime performance isn't everything, and it's typically better to opt-into devirtualization rather than to opt-out of it.
    • bccdee 5y ago
      You must have absurd standards if you find dynamic dispatch to be unacceptably slow. Also, yeah, not every function call needs to be inlined. One level of indirection on top of jumping into a new function isn't really much overhead at all, unless you're doing it for literally every function call.
    • kaba0 5y ago
      As opposed to passing function pointers everywhere, callback hell and friends? Or which language does it well in your opinion? The fact is, dynamic dispatch is needed, because not everything can be known at compile time. And as in a recent thread a HNer rightly noted (could not find it where I read it), the actually expensive thing in programming is flexibility.
• throwaway894345 5y ago
  Disagree. Go and Rust both have dynamic dispatch and neither have the problems that inheritance has. Even in C which lacks dynamic dispatch, people will either try to build it at the expense of type safety or they will try to manage an impossibly complex implicit state machine (I've seen this in a lot of critical real time systems).
  • kaba0 5y ago
    I would wager that in most ordinary C programs it is worse. You can’t even reason about code anymore with all the callbacks.
• AdieuToLogic 5y ago
  > Inheritance isn't the root of all evil, dynamic dispatch is. It's a remarkably powerful implementation detail but one with enormous cost ... Dynamic dispatching typically costs one pointer lookup in a vtable[0]. By "typically", I specifically mean "in any production quality run-time environment." This is not an "enormous cost" by any reasonable definition. 0 - https://en.wikipedia.org/wiki/Virtual_method_table https://en.wikipedia.org/wiki/Virtual_method_table