Re: Objective-C 2.0

[Richard Frith-Macdonald]

On 2 Sep 2009, at 12:17, Michael Thaler wrote:

> Hi,
>
> I am currently learning Objective-C on the Mac (using that book:-))  
> and I was
> wondering if Objective-C 2.0 is available on Linux and if it can be  
> used for
> gnustep development.
>
> If it is available is it ok to use it for gnustep? If it is not  
> available, are
> there any plans to support it?

It's not available.  There are people working on different bits of it,  
but no concerted plan.

> I think especially having a garbage collector
> would be quite interesting. Personally I think having a GC would be a
> sustantial advantage of gnustep over, e.g. Qt.

GNUstep has GC support in the make package and base library, but  
nowhere else.
It's not quite the same as Apple's implementation, but shares most of  
the same API.
I have to say that GC has to be considered at best beta-test quality  
and getting it working four you would probably take some effort.

> If it is partly available, which features can (should) be used? Are  
> blocks
> available (which seem to be a propertery Apple extension to C-like  
> languages)?

I would avoid most of the new features.  Largely the gcc compiler  
doesn't support them (though David Chisnall is working on adding  
support for a lot to Clang).  Often the new features are arguably bad.
You should be able to use fast enumeration (the API is there in  
gnustep-base, even of the lack of compiler support means that you  
won't actually get the promised performance benefit).  You should be  
able to use GC with some work.
I'd avoid using properties ... even if/when we do get support for  
properties, I'd argue that they do more harm to code clarity/design  
than can be compensated for by their advantages.

> Is it possible to write applications that can be compiled on both  
> the Mac
> using Cocoa and Linux using gnustep?

Sure ... very easy ... just develop on GNUstep and then build from the  
GNUstep source on the Mac.
Doing it the other way round is the harder way as it's much easier to  
find yourself writing non-portable code on the Mac, but if you stick  
strictly to the Cocoa APis (the older ones) you would probably be OK.