obj-c runtime and language bindings.

[Pascal J . Bourguignon]

Daniel Rogers writes:
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> 
> hi --
> 
> How well does the objective-c runtime lend it self to language bindings?
> ~ Specifically, is the object data structures well defined?  Can
> inheritance be defined with a function call?  Do language binding have
> to get chummy with the compiler to handle inheritance?  Can a language
> binding create a derived type of an objective-c class, then have another
> objective-c class derive from the forgien language binding?
> 
> Basically, I am curious if objective-c can handle language bindings like
> gobject can.

Objective-C  runtime  is  defined  in  pure  C.   Contrarily  to  C++,
Objective-C is a _strict_ superset of C.  That is, you can compile any
C  program  with an  Objective-C  compiler  AND  obtain a  meaningfull
executable, which can't  be said of C++.  

So  any  external  binding you  can  write  in  C,  you can  write  in
Objective-C because it's written exactly the same.

On the other hand, if  you want to handle Objective-C classes, objects
and messages from another languages that can bind to C functions, then
there's no problem other than there is no _standard_ runtime API.

That means that you can do it without any difficulty, but it will only
work for the runtime you choose: Apple's or GNU's.  On the other hand,
since there  remain only two  Objective-C runtimes alive, it's  no big
deal to implement bindings for both, and they're not much different.

For an example,  you may have a  look at guile, or at  the bindings to
Apple's Objective-C runtime from OpenMCL (CCL).


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