3 ms·

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.