CTFE and DI: The Crossroads of D

[Adam Wilson]

On Thu, 10 May 2012 11:25:11 -0700, deadalnix <deadalnix at gmail.com> wrote:

> Le 10/05/2012 19:51, Steven Schveighoffer a écrit :
>> On Thu, 10 May 2012 13:27:23 -0400, deadalnix <deadalnix at gmail.com>  
>> wrote:
>>
>>> Le 10/05/2012 18:56, Steven Schveighoffer a écrit :
>>>> There is already a better tool -- cp. I ask again, what is the benefit
>>>> of .di generation if it is mostly a glorified (faulty?) copy  
>>>> operation?
>>>>
>>>
>>> Please stop with that cp argument, this is complete bullshit.
>>
>> Not complete. Maybe it's somewhat of an exaggeration ;)
>>
>> But really, I look at the current situation that started this thread.
>> The intention of .di header generation retaining implementation is to
>> allow for inlining, not making CTFE available. Yet a side effect is that
>> sometimes CTFE *is* available.
>>
>> Well, let's say something becomes uninlinable, and now dmd decides to
>> remove its implementation. But another piece of code is already
>> depending on that source to be available for CTFE! Now you have broken
>> code inadvertently, and the only way to fix it is to hand-edit the .di
>> file.
>>
>
> The di generator can remove code that isn't CTFEable (at least can be  
> proven to not be CTFEable). It is the case in your example.

False. No semantic analysis has been performed therefore DMD has no idea  
what is and is not CTFEable.

>> But the compiler should stay out of the decision to strip or not based
>> on optimization predictions.
>>
>
> The compiler should provide something by default. It is up to the user  
> to mark the code accordingly.

This is pretty much what we are advocating with the attribute solution.

>> I agree the module system is way better than having an interface and
>> implementation file separate. But when you actually *do* want it to be
>> separate (for whatever reason), D pretty much devolves to C.
>>
>
> At least it is not worse.

Does not D strive to be better than C++, much less C? I think we can do  
better with DI's too.

-- 
Adam Wilson
IRC: LightBender
Project Coordinator
The Horizon Project
http://www.thehorizonproject.org/