On 5 Feb 2004, at 23:55, Avi Bryant wrote:

>
> On Feb 5, 2004, at 3:43 PM, Marcel Weiher wrote:
>
>>
>> On 5 Feb 2004, at 19:38, Avi Bryant wrote:
>>>
>>> But, really, we should just do a decent ObjC bridge one of these 
>>> days...
>>
>> If there is actual interest, I'd be happy to restart work on that...
>>
>> What do you find indecent about the current one?
>>
>> It really isn't all that pretty, but tends to do everything you can 
>> easily do without overcoming Squeak's not being re-entrant.
>
> I'm definitely interested... in fact I'm sitting here right now with 
> VMMaker open thinking about starting to work on one.
> The main things I don't like about the current one:
> - it doesn't seem to work with recent VMs.  This is probably easily 
> fixed, but it would be a good start to have a prebuilt 3.6 VM with a 
> working ObjectiveCPlugin.

OK, interest in CocoaSqueak seemed to have pretty much evaporated, so 
there didn't seem much point in making new releases, especially as I've 
also been very busy with a new job and my move to London..

> - it doesn't allow message sends from ObjC to Squeak objects.  This is 
> what you're talking about with "not re-entrant", but to me that's a 
> very necessary part (the only point to me of an ObjC bridge is to 
> build Cocoa UIs, and that requires being able to get callbacks and 
> delegation messages AFAIK).

Yup, precisely.  Well, I can also see other uses, but that's a major 
part of it.

>   This will require some thread and semaphore stuff, but it's 
> certainly doable.

Yes, that is also the way I had seen:

  - have (at least) two threads.
  - when Squeak calls out
       - save the message parameters
       - pass on to second thread that sends the Objective-C message
       - return into Squeak
       - suspend the Squeak-internal process making the call (on a 
semaphore)
       - when the Objective-C message returns, that thread signals the 
semaphore
       - the Squeak process awakes and picks up the result

- for call-in to squeak, either
       -(ab-)use the even mechanism
       - or use a separate semaphore and pick up the necessary 
arguments, dispatch, return etc.


The proxies representing Squeak objects on the Objective-C side have to 
refer to them via the (an?) external object table, in order to properly 
handle object-pointers moving around during GC.

Of course, Andreas has raised an intriguing possibility of doing this 
without separate threads.

> Also nice would be compatibility methods for easy bridging between 
> String/NSString, Array/NSArray, OrderedCollection/NSMutableArray, 
> Dictionary/NSMutableDictionary, etc.

Yes, and what would be really nice if the runtimes could just 
integrate...

Cheers,

Marcel