D-Cocoa Port

[Jacob Carlborg]

On 2012-04-13 15:34, Rizo Isrof wrote:
> Hi,
>
> I am planning to use D for creating native applications on Mac OS X. For
> that, of course, D must interact with the Cocoa API. I have no knowledge
> of how this bindings could be done. I've already looked at Cocado[1] and
> do know the Michel Fortin's D-ObjC bridge[2], and would like to be
> enlightened about some details:
> * What is their (or any other possible) approach of porting Cocoa to D?
> -- here I essentially ask for technical reading sources
> (books/articles/references, etc);

There are three ways (two deepening on how you look at it).

1. Use the Objective-C runtime manually, which is implement with regular 
C functions.

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html

2. Use a bridge that handles everything nicely. The bridge uses the same 
implementation as in the first way. The bridge also performs type 
conversions automatically and other things to ease the development.

http://www.dsource.org/projects/dstep
http://michelf.com/projects/d-objc-bridge/

3. Implement direct support in the language to be compatible with 
Objective-C. This is what Michel Fortin did here:

http://michelf.com/projects/d-objc/
(Note, this is not a bridge)

He forked DMD and added support for extern(Objective-C) which will 
output code similar to what GCC/Clang would do. This is a more direct 
way to interface with Objective-C and won't add any more overhead than 
using Objective-C directly would. I guess this would mean the ABI's are 
compatible.

> * Is it possible to establish an ABI compatibility with ObjC directly or
> through the C ABI? -- There's a question on _stackoverflow_[3] where the
> answers describe what could be achieved with Objective-C's Runtime
> Reference[4];

Both are possible, see above.

> * Is it feasible to make this kind of stuff work nicely and get the
> level of performance and stability like, e.g., with Qt framework on Mac
> OS X?

I think so if you use Michel's fork of DMD.

> I have no experience at all in this field so forgive me any technical
> faults. Any help would be appreciable.
>
> Thanks in advance for your responses.

I think the best way is to use the third one mentioned in the list 
above. Note that this is based on an older version of DMD. The project 
is not finished yet and is currently on old. Although an alpha version 
has been released.

The problem with a bridge is the it cause way to much bloat. A Hello 
World application written using a bridge generated a 60MB executable.

Using the Objective-C runtime manually is just too verbose and tedious. 
If you are interested in this you can have a look at my documentation of 
how my Objective-c/D bridge works and is implemented:

http://www.dsource.org/projects/dstep/wiki/ObjcBridge/BridgeInternals

> [1]: http://sourceforge.net/projects/cocodao/
> [2]: http://michelf.com/projects/d-objc/

Note, this is not a bridge. This is third one mentioned in the list above.

> [3]: http://stackoverflow.com/questions/5901508/calling-cocoa-apis-from-c
> [4]:
> http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html
>
>
> - Rizo


-- 
/Jacob Carlborg