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The other thing that ObjC does right is that it builds on top of an unmodified C (unlike C++ which went full in, messed everything up and now needs the C++ stan

The other thing that ObjC does right is that it builds on top of an unmodified C (unlike C++ which went full in, messed everything up and now needs the C++ standard to change to integrate new C features, which then usually ends up as half-assed and incomplete attempt - see designated initalization). C and ObjC can be improved independently from each other, and combining them "just works" without "harmonization efforts" by language committees. Also, doesn't the existance of ARC mean that ObjC supports better "static lifetime analysis" than C++? Or is C++ just behind the curve there?

jb1991 3y ago
ARC is runtime reference counting. How does that offer static lifetime analysis? C++ also has a form of ARC in the form of shared pointers, the only difference is that in C++ it's opt-in while in ObjC/Swift ARC it's just the way it is.
- flohofwoe 3y ago
  ARC does static lifetime tracking (or maybe better: ownership tracking) to remove redundant reference counting operations (highly simplfied: it basically makes the decision for you when to use the equivalent of a shared_ptr or unique_ptr under the hood - which is at least nice for API design, since functions just take or return generic "object references" instead of raw, shared or unique pointers like in C++ (which then is usually not what the caller wants in a specific situation). ARC is not perfect because it has to be fairly conservative (it can be manually tuned though), but ObjC still seems to give the compiler more static information than shared_ptr and unique_ptr in C++ which are purely stdlib runtime constructs.
  - jb1991 3y ago
    I'd imagine Swift also does this?
    - flohofwoe 3y ago
      AFAIK Swift's ARC is the same thing, yeah.
- pjmlp 3y ago
  Objective-C has an advantage, the compiler is able to elide retain/release pairs due to ARC semantics, where in C++ there is no special semantics defined in ISO C++ for smart pointer classes.

jb1991 3y ago

ARC is runtime reference counting. How does that offer static lifetime analysis? C++ also has a form of ARC in the form of shared pointers, the only difference is that in C++ it's opt-in while in ObjC/Swift ARC it's just the way it is.

flohofwoe 3y ago
ARC does static lifetime tracking (or maybe better: ownership tracking) to remove redundant reference counting operations (highly simplfied: it basically makes the decision for you when to use the equivalent of a shared_ptr or unique_ptr under the hood - which is at least nice for API design, since functions just take or return generic "object references" instead of raw, shared or unique pointers like in C++ (which then is usually not what the caller wants in a specific situation). ARC is not perfect because it has to be fairly conservative (it can be manually tuned though), but ObjC still seems to give the compiler more static information than shared_ptr and unique_ptr in C++ which are purely stdlib runtime constructs.
- jb1991 3y ago
  I'd imagine Swift also does this?
  - flohofwoe 3y ago
    AFAIK Swift's ARC is the same thing, yeah.
pjmlp 3y ago
Objective-C has an advantage, the compiler is able to elide retain/release pairs due to ARC semantics, where in C++ there is no special semantics defined in ISO C++ for smart pointer classes.