Future of Descent and D Eclipse IDE

[Bruno Medeiros]

On 25/05/2010 03:15, Ary Borenszweig wrote:
> On 05/24/2010 08:38 AM, Bruno Medeiros wrote:
>
> * Porting DMD source to Java was done manually and it's a very boring
> and long task, and we need to find a way to automate it if we'd like to
> support really good integration with the language (I mean, real semantic
> value, and because D is not dynamic I think this is worth it).
> * The DMD source was modified a little bit for performance reasons and
> for integration with Descent so now it contains bugs that are very hard
> to fix.

That's actually exactly the concerns I had from the start with doing 
that approach. Even if we had an easy way to automate the port, I think 
we would still have a code that has issues of performance and 
scalability. And yet if we would try to modify it to address those 
issues, we would most likely introduce hard to correct bugs, and/or make 
the automated porting process (if we had one) much more complicated, if 
not impossible (aka, reverting to doing a lot of manual work).

That's why I think the approach of porting the full DMD frontend is not 
good, even it was more automated. So for me its either:

  * Port and use the DMD parser only, and implement semantic analysys 
features by scratch. This is Mmrnmhrm's current approach, and would mean 
the semantic capabilities would be much less than Descent: likely just 
resolving references (for code completion), but no semantic errors or 
CTFE debug.

  * Try and build the parser and semantic engine with the help of some 
other tool, like IMP for example.

I'll have to take a look at IMP again to think about this some more.

> * The code is just too big because it has a lot of code from JDT,
> modified a little bit, and that makes it hard for other developers to join.
>
> .. This means I'm currently
>> the only Eclipse developer, so I could just do things in the way I'm
>> thinking of, but Ary, I would still like to get your input, because I
>> hope one day you might be interested in coming back to Descent
>> development. :)
>
> I can program now and then if I have time, but what I'd really like is
> to plan how to start things almost from scratch and think of a plan of
> doing it well. Maybe Descent could be done with IMP, I don't think using
> JDT's source code will be good for the project. The only problem I see
> with IMP (or DLTK) is that they don't support some of the features
> Descent already provides... but as IMP gets better Descent will
> automatically get those updates.
>

Yes, this is the other issue is how to do all the IDE infrastructure 
stuff. I also think that porting JDT is less than ideal. Porting JDT has 
similar problems to the DMD approach (although to a much lesser degree). 
The code is not easy to understand, and we risk introducing bugs. And it 
is also hard to maintain and keep updated with new JDT versions.
If there was no project such as IMP or DLTK, I think it would still be 
worth to do the JDT porting. But since those projects exist and are 
currently actively developed, I think they are a much better choice.
In the cases where they don't provide the features that Descent already 
supports, I think that we might be able to do a little bit of 
mix-and-match, and use a some of JDT's ported code. But the feasibility 
of that will depend a lot on the particular feature, and whether IMP or 
DLTK is used.

As for which to use, I'm still inclined torwards DLTK. DLTK has more IDE 
infrastructure support and functionality than IMP, and might make it 
easier to mix-and-match with JDT porting, since a lot of DLTK itself is 
also based on JDT ported code. We might even submit contributions to 
DLTK itself. But it has no support for parsing or language semantic 
analysis, which IMP has. So that's an advantage for IMP.
But I'll have to take another look at IMP (an also the new DLTK version, 
since I'm not yet familiar with all the changes that have occurred in 
the last year or so).


>
>>
>> Ary, I would like to know if by any chance you are interested in doing
>> that separation in the near future. If not, I can do it myself, but it
>> might take a bit longer.
>
> Yes, I would like to do it, but first I think we need to think if we
> want to a) keep using the Java port and little by little upgrade it to
> the latest dmd versions, b) start another port but build a tool to more
> or less automate that process (Frank Benoit started something in that
> regard but I don't know what happened then) or c) make a less
> semantic-aware IDE like Mmrnmhrm (the good thing is that it might be
> simpler and faster, but the bad thing is that we might not get all the
> features we'd want).
>
> Thanks for bringing this topic! A lot of effort has been put in Descent
> and it would maybe be sad if the project is abandoned... (but I really
> feel I'm stuck now and I don't know how to advance... or at least I know
> I would have to keep porting C++ code to Java, but...
>
> http://www.explosm.net/comics/1804/
>
> )
>
> Cheers!

Cool to see you a bit more re-motivated. :)


So let me say what I want to do next: Mmrnmrhm at the moment has no 
support for D2 whatsoever (well its not completely unusable, one can 
open D2 files but it will treat them as D1 files). I want to take the 
current Descent parser, and update Mmrnmrhm's semantic engine to this 
new parser version, such that Mmrnmrhm's current semantic functionality 
(go to references, find references) works in D2 as well. While doing 
this, it should give a good idea of how complex it is to keep up the 
basic IDE functionality on par with language changes, with the approach 
of implementing the code by scratch. I'm confident this can be done 
without much effort, and thus it would validate itself as the best approach.


-- 
Bruno Medeiros - Software Engineer