JShell: source in langtools vs JDK?

[Jonathan Gibbons]

I didn't say I think JShell should be in langtools, and I thought I was 
being careful to be very explicit about that. I was just trying to make 
sure we were making the right choice for the right reasons.

The fact that it depends on JDI and jline is IMO a red herring. If they 
were both already in JDK 8 (i.e. the boot JDK) would we be having this 
discussion?

To me, the bottom line is that I don't think it matters where the code 
lives, and as a result I personally don't care and have no opinion where 
the code should live. I /do/ think that whereever we choose to put it, 
we can make everything work well from a developer standpoint, without 
inconveniencing any existing developer usage, although I concede that we 
might choose not to integrate it with the langtools make/build.xml 
infrastructure and/or the existing NetBeans project.  And from a 
somewhat selfish standpoint, I think we have somewhat more latitude to 
set things up the way we like it in the langtools repo than we would in 
the jdk repo.

I agree that JShell is higher up in the layers of abstraction than 
javac, but I also don't think that the langtools repo is defined to be 
"core tools to be able to work with the JDK". The provenance of the repo 
(as indicated by its name) is that it was code that was managed by the 
old Sun Language Tools Group, from way back when, meaning that it was 
more of a "team" repository than a repository defined by a layer of 
abstraction.

So, for me, I think this comes down to, "where does the Kulla dev team 
think it would be most convenient for them to keep and work on the 
code?". Once we can answer that, we can move on to, "what is the most 
convenient way to satisfy all the requirements of all the interested 
parties?"

-- Jon


On 09/16/2015 04:02 PM, Maurizio Cimadamore wrote:
> Jon, let's reverse the question - why do you think it *should* live in 
> langtools? Honestly it feels very different from all other tools that 
> live there; there's dependencies on JDI, jline - so to me it feels 
> closer to other tools (i.e. jconsole) which already are in the jdk 
> repo. I guess my argument is - if langtools defines the core tools to 
> be able to work with the JDK, jshell feels like one ore two layer of 
> abstractions on top of that.
>
> Maurizio
>
> On 16/09/15 23:31, Jonathan Gibbons wrote:
>>
>>
>> On 09/16/2015 03:06 PM, Robert Field wrote:
>>> As part of the JShell code review, Maurizio made the case that 
>>> JShell should be in the JDK repo rather than langtools repo (where 
>>> it is in the Kulla workspace).  We would like additional feedback on 
>>> this before proceeding --
>>>
>>>> On Sep 11, 2015, at 8:25 AM, Maurizio Cimadamore 
>>>> <maurizio.cimadamore at oracle.com> wrote:
>>>>
>>>> One general high-level comment, which I also pointed out elsewhere, 
>>>> is that I'm not sure jshell really belongs in langtools; while it's 
>>>> semantically (obviously) related to langtools - it is a rather 
>>>> different beasts w.r.t. all other tools in langtools-land; the fact 
>>>> that it depends on the JDK (for jline, and for JDI in general) 
>>>> makes it very hard to run on top of a random JDK and then 
>>>> bootstrapping classes - which is a technique widely used to be able 
>>>> to run langtools tools w/o having to do a full build cycle. More 
>>>> specifically, talking about IDE integration, I don't see how 
>>>> IntelliJ/Netbeans langtools projects (and the langtools internal 
>>>> developer ant build) could be updated to be able to run/debug 
>>>> jshell w/o a full build.
>>>
>>>
>>
>> In the Big Picture view of the universe, folk would like to 
>> restructure the repos in an OPenJDK forest, at which point the 
>> distinction between the langtools and jdk repos will likely 
>> disappear, or at least become very (very) blurred.  While that change 
>> is not imminent, IMO opinion, it significantly reduces the impact of 
>> the reasons why JShell should not be in langtools.
>>
>> I also don't entirely agree with the IDE reasons either.  If you want 
>> to work on JShell in an IDE, you're going to have to do what it takes 
>> to get rid of the red squiggly lines anyway, whatever repo the code 
>> is in. To keep JShell out of Langtools because it doesn't fit our 
>> current methodologies is a case of the tail wagging the dog.
>>
>> Also, I note that JDK 9 now builds the product module by module. In 
>> times past, we built the world repo by repo, and that would indeed 
>> have been good reason to keep JShell out of langtools, because of the 
>> dependencies of JShell on JDK 9 API, like jline. But now, the build 
>> will build "interim javac", and can then build JDK modules like 
>> java.base and whatever module jline ends up in, and can then build 
>> the module containing JShell.
>>
>> As to how to organize IDE projects, in the worst case, we keep the 
>> langtools IDE setup as it is now (no JShell) and have a separate 
>> project for JShell itself. That is tantamount to what we would do if 
>> we push JShell into the jdk repo.
>>
>> So, I'm saying all that while trying to be agnostic on which repo it 
>> should live in.    I don't really agree with the stated reasons why 
>> it should not live in langtools, which means that we can look for 
>> other reasons to choose one repo or another.
>>
>> -- Jon
>