Home/ Questions/Q 7921057
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-03T16:26:35+00:00

I have searched around for a while, but surprised that no one ever popped

  • 0

I have searched around for a while, but surprised that no one ever popped this question, so here I go:

I have a Objective-C method that takes an id argument. Now I want to use respondsToSelector: to determine if it is valid for following actions, if it is not not I have a backup plan for it. (Which is not ASSERT(0) :P)

So, when someone tries to mess up with me and pass an (id)someC++Object, I’ve got a big crash, of course.

My question is simply: Can I make a C++ object fail a respondsToSelector: safely so that I can use my backup plan (punching the coder in the face for one)?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    In short, you can’t.

    At least, not reliably and not in any sane way. Nor, frankly, should bother; that level of defensive programming is utterly futile in the face of a C based language.

    At the least, you would need to:

    • validate that the pointer is pointing to accessible memory
    • pointing to a current allocation
    • the first address sized chunk points to an Objective-C class (including derived classes, possibly)

    In general, any code that makes heavy use of isKindOfClass: and respondsToSelector: (outside of the delegation pattern) is quite atypical to the norms of Objective-C design patterns.

    Or, to put it another way, you have a static type checking compiler that is quite good at checking lots of validity parameters at compile time. Use it.

    • 0