Re: GnuStep Runtime vs. et. al.

[Nicola Pero]

Hi,

> Could someone please explain the _runtime_ differences of Gnustep, Darwin
> ObjC runtime and POC?

ahm - gnustep and apple stuff are different but similar, POC instead is on
its own.  Also, gnustep and apple stuff have a similar higher level
framework (gnustep-base/Foundation) built on top on the runtimes, so
porting from one environment to the other one should be quite easy - or
even if not easy anyway the two environments have similar designs and
similar facilities - while POC is definitely different.
<whispering>suggestion from the heart - don't use POC - go with the
standard good GNU (or Apple) stuff</whispering>


> It seems obvious that the goal would be to have one runtime and compilation
> strategy across multiple platforms with minimum porting effort.  

Ahm - if you don't access the runtime directly but only through an higher
level layer (such as gnustep-base or Apple's Foundation Framework) then
you should not need to modify your code to run with a different runtime,
because your application/tool is isolated from the actual runtime details
by the framework. 

For example, if you port gnustep-base to run on the Apple runtime (I think
some sort of effort in this thing is underway), your Objective-C code
which uses gnustep-base can then happily work with the Apple runtime
without changes.  You don't need to modify your application code.  You
only port the base library which is what the application code is using. 

Or, if you port your code from gnustep-base to run with Apple's Foundation
Framework, which shouldn't require too much of an effort - it might
actually only need modifications in the makefiles (even if I've never
actually used an Apple computer so that's only what I heard people
saying), then your code will automatically use Apple's runtime.


> Anyone know where I can find the technical
> details of compilation / runtimes of Objective C implementations?

Well - if you are interested in the details of the GNU Objective-C
runtime, the best thing is - grab the GCC sources, and look into the
libobjc/ directory - the runtime is there.  It might not be particularly
well documented, but the code is generally not too difficult to read; and
it's quite interesting.

The Apple's runtime sources are available as well for reading - they are
somewhere on Apple's Darwin site.