As some of you might know Michel Fortin created a fork of DMD a couple of years ago which add support for using Objective-C classes and calling Objective-C method. That is making D ABI compatible with Objective-C.

I have now updated it to the latest version of DMD and druntime. All D/Objective-C tests pass and all standard tests pass. I'm planning to create a DIP for this and would really like this to be folded into main line. For know you can read the design document created by Michel:

http://michelf.ca/projects/d-objc/syntax/

Original project page: http://michelf.ca/projects/d-objc/

My forks:
DMD: https://github.com/jacob-carlborg/dmd/tree/d-objc
druntime: https://github.com/jacob-carlborg/druntime/tree/d-objc
Phobos: standard Phobos, commit f85bd54ef5615986960fdd68ea87c8aaf5c5118d

Currently I have limited bandwidth and cannot upload a pre-compiled binary. To compile use the following commands:

cd dmd/src
make -f posix.mak MODEL=32 D_OBJC=1

cd druntime
make -f posix.mak DMD=../dmd/src/dmd MODEL=32 D_OBJC=1

cd phobos
make -f posix.mak DMD=../dmd/src/dmd MODEL=32

Currently D/Objc only works for 32bit. You can use Michel's example application, Chocolate, to try it out. It's a bit cumbersome to compile without Xcode but it's possible.

http://littoral.michelf.ca/code/d-objc/chocolate-dobjc-a1.zip

-- 
/Jacob Carlborg

Jacob Carlborg:

> http://michelf.ca/projects/d-objc/syntax/

Instead of:
extern (Objective-C)

Is it better to use a naming more D-idiomatic?

extern (Objective_C)


Regarding this syntax:

void insertItem(ObjcObject object, NSInteger value) [insertItemWithObjectValue:atIndex:];

Is it possible and good to replace it with some UDA?


> I'm planning to create a DIP for this and would really like this to be folded into main line.

It seems contain some different things/syntax. I don't know how much Walter&Co will appreciate it.

Bye,
bearophile

On 6/23/2013 1:24 PM, Jacob Carlborg wrote:
> As some of you might know Michel Fortin created a fork of DMD a couple of years
> ago which add support for using Objective-C classes and calling Objective-C
> method. That is making D ABI compatible with Objective-C.
>
> I have now updated it to the latest version of DMD and druntime. All
> D/Objective-C tests pass and all standard tests pass. I'm planning to create a
> DIP for this and would really like this to be folded into main line. For know
> you can read the design document created by Michel:

Thank you for reviving this. Please carry on!

On 2013-06-23, 23:02, bearophile wrote:

> Jacob Carlborg:
>
>> http://michelf.ca/projects/d-objc/syntax/
>
> Instead of:
> extern (Objective-C)
>
> Is it better to use a naming more D-idiomatic?
>
> extern (Objective_C)

There's already some precedence in extern (C++).

-- 
Simen

On 2013-06-23 23:02, bearophile wrote:

> Instead of:
> extern (Objective-C)
>
> Is it better to use a naming more D-idiomatic?
>
> extern (Objective_C)

As Simen said, we already have extern (C++). But I can absolutely change this if people wants to.

> Regarding this syntax:
>
> void insertItem(ObjcObject object, NSInteger value)
> [insertItemWithObjectValue:atIndex:];
>
> Is it possible and good to replace it with some UDA?

We could use an attribute. But I don't think it would be possible to use an UDA. Currently the compiler doesn't know anything about a particular UDA, all UDA's are treated the same. It it's either a built in attribute or an UDA. Doing something in between would be a lot harder.

> It seems contain some different things/syntax. I don't know how much
> Walter&Co will appreciate it.

I would say that it's very little new syntax, surprisingly. But semantically there's a lot of new stuff. But the core things are just the same as with extern (C), making D ABI compatible with another language, Objective-C. I think that this is mostly is a non-breaking change. All new keywords are prefix with two underscores, which is reserved by the compiler. A lot of stuff only apply for classes/methods declared as extern (Objective-C).

* extern (Objective-C) - I wouldn't really consider this new syntax

* [foo:bar:] - New syntax. Does not have to use this exact syntax but the functionality it provides is essential.

* Constructors in interfaces - Not really a new syntax. Just allows an existing syntax to be used in a new place.

* Foo.class - I guess this technically is new syntax. The only thing making this new syntax is the use of keyword. I we really don't want this we could rename it to __class or similar.

* __classext - Not implement yet, so that's up for discussion

* String literals - No new syntax. Just an implicit conversion added

* BOOL __selector(NSString) - New syntax. Kind of essential to have.

* Foo.protocolof - Not really a new syntax either. I don't think this is as essential as the other features.

* @IBOutlet and @IBAction - Not implemented. This could possibly be implemented as dummy UDA's.

* Blocks - Not implemented. I'm wondering if we could use the delegate keyword for this. If a delegate is marked as extern (Objective-C) it's a block. Or that might perhaps be confusing.

-- 
/Jacob Carlborg

On 2013-06-23 23:12, Walter Bright wrote:

> Thank you for reviving this. Please carry on!

Is there a chance we can get this into main line?

-- 
/Jacob Carlborg

On 2013-06-23 20:24:41 +0000, Jacob Carlborg <doob@me.com> said:

> As some of you might know Michel Fortin created a fork of DMD a couple of years ago which add support for using Objective-C classes and calling Objective-C method. That is making D ABI compatible with Objective-C.
> 
> I have now updated it to the latest version of DMD and druntime. All D/Objective-C tests pass and all standard tests pass.

I know it was significant work to make it both play nice with the most recent OS X linker and port it to the newest DMD code base. Great achievement.

-- 
Michel Fortin
michel.fortin@michelf.ca
http://michelf.ca/

On 2013-06-24 10:04:01 +0000, Jacob Carlborg <doob@me.com> said:

>> Regarding this syntax:
>> 
>> void insertItem(ObjcObject object, NSInteger value)
>> [insertItemWithObjectValue:atIndex:];
>> 
>> Is it possible and good to replace it with some UDA?
> 
> We could use an attribute. But I don't think it would be possible to use an UDA. Currently the compiler doesn't know anything about a particular UDA, all UDA's are treated the same. It it's either a built in attribute or an UDA. Doing something in between would be a lot harder.

Not necessarily. There's a couple of Objective-C classes that get special treatment by the compiler (identified by a pragma). One could do the same for an UDA so the compiler would know where to get that value. I'd surely have implemented it as an UDA if such a thing existed at the time.

Perhaps we should use a string UDA. ;-) (joke)

>> It seems contain some different things/syntax. I don't know how much
>> Walter&Co will appreciate it.
> 
> I would say that it's very little new syntax, surprisingly. But semantically there's a lot of new stuff. But the core things are just the same as with extern (C), making D ABI compatible with another language, Objective-C. I think that this is mostly is a non-breaking change.

It indeed is an additive and non-breaking change.

> All new keywords are prefix with two underscores, which is reserved by the compiler. A lot of stuff only apply for classes/methods declared as extern (Objective-C).
> 
> * extern (Objective-C) - I wouldn't really consider this new syntax
> 
> * [foo:bar:] - New syntax. Does not have to use this exact syntax but the functionality it provides is essential.
> 
> * Constructors in interfaces - Not really a new syntax. Just allows an existing syntax to be used in a new place.

And it's only allowed in extern (Objective-C) interfaces because it does not make much sense for D interfaces.

> * Foo.class - I guess this technically is new syntax. The only thing making this new syntax is the use of keyword. I we really don't want this we could rename it to __class or similar.

It is a new syntax. This "function" needs special semantic treatment by the compiler because it returns an object of a different class depending on the type or object you're calling it on. It also mirrors the method named "class" in Objective-C. Given these data points, it seemed appropriate to use the class keyword, which hints at the compiler magic. Hence why I tweaked the syntax to allow ".class" on Objective-C classes and objects.

> * __classext - Not implement yet, so that's up for discussion
> 
> * String literals - No new syntax. Just an implicit conversion added

I'm particularly proud of those string literals. They're way cleaner than their Objective-C counterparts.  :-)

> * BOOL __selector(NSString) - New syntax. Kind of essential to have.

Those too are better than their Objective-C counterpart too as they carry the argument and return type, making them less error-prone.

> * Foo.protocolof - Not really a new syntax either. I don't think this is as essential as the other features.

It gives you the pointer for protocol (interface) Foo. You need that if you want to check at runtime if a class conforms to this protocol (or implements this interface in D parlance).

> * @IBOutlet and @IBAction - Not implemented. This could possibly be implemented as dummy UDA's.
> 
> * Blocks - Not implemented. I'm wondering if we could use the delegate keyword for this. If a delegate is marked as extern (Objective-C) it's a block. Or that might perhaps be confusing.

Blocks are reference-counted and don't share the two-pointer layout of a delegate. I'm not sure it'd be wise to call them delegates. But this needs some more thinking.

Finally, there is a couple of features that were added to Objective-C since then that should be added to the todo list to keep feature parity. Some of those, if implemented right, could benefit the rest of D too. For instance: ARC (automatic reference counting) which is becoming a must in Objective-C.

-- 
Michel Fortin
michel.fortin@michelf.ca
http://michelf.ca/

On 2013-06-24 14:49, Michel Fortin wrote:

> I know it was significant work to make it both play nice with the most
> recent OS X linker and port it to the newest DMD code base. Great
> achievement.

Thank you for all the help I've got and for you starting with this whole project.

-- 
/Jacob Carlborg

On 6/24/2013 3:04 AM, Jacob Carlborg wrote:
> On 2013-06-23 23:12, Walter Bright wrote:
>
>> Thank you for reviving this. Please carry on!
>
> Is there a chance we can get this into main line?

Yes, but since I don't know much about O-C programming, the feature should be labeled "experimental" until we're sure it's the right design.