Re: Embed ObjC in an API library?

[Helge Hess]

Kaelin Colclasure wrote:
> Is it possible to implement a set of functions in Objective C, and then 
> wrap them with a plain-old C interface and package them as a shared 
> library?

Yes. You actually only need to wrap them to make it more convenient for 
the C-developer. You can call any Objective-C method/class in ANSI-C by 
using the Objective-C runtime, eg:

  #include <objc/objc.h>

  objc_msg_lookup(myObject, sel_get_uid("doIt:"))
    (myObject, myArg);

Of course it probably makes more sense to wrap that, eg in

wrapper.m:
  void MyObject_doIt(id myObject, int arg) {
    [myObject doIt:arg];
  }

wrapper.h:
  extern void MyObject_doIt(id myObject, int arg);

Personally I would really like to see a full, supported and stable 
ANSI-C API to Foundation, since that makes embedding easier.

> And if it is, would one be able to use the GNUstep foundation 
> classes in such an endeavor?

Yes. But of course you need to provide a proper environment and you 
probably need to call some initializers.

> And finally, would one be able to pull this
> off on Win32 as well?

Yes, why not. You just need to link against all relevant DLLs, like 
libobjc and libgstep-base.

regards,
  Helge
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Helge Hess                         Email:    helge.hess@skyrix.com
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