Bug 562889 - Investigate support for tpd target files

[laeubi]

See https://bugs.eclipse.org/bugs/show_bug.cgi?id=562889

[akurtakov]

I think we can close this one. Can tpd files even cope with direct maven deps at all?

[laeubi]

There is at least a feature request for this: eclipse-cbi/targetplatform-dsl#115
I think @mbarbero might be able to give more insights about future plans for TPD and user-base...

As described in the original bugzilla, tycho should be able to reuse the TPD plugin to first generate a temporary target and then simply read this one...

[HannesWell]

As already written in M2E I think in general it would better to enhance the capabilities of PDE's standard InstallableUnit container and also enhance the tool support for it, so that in the end one can work in the Target Definition Editor's Source tab like in the TPD-Editor. In the end it should be like the TPD just with XML Syntax, so that the TPD becomes obsolete.

Actually I'm a big fan of the TPD and the workflow is really great, but we should not add extra work and code to support two formats when we already have duplicated work to support one format in the IDE (PDE, M2E, ...) and Tycho.

Christoph already added support for references to other *.target-files to PDE recently that was just released with Eclipse 2022-03. So IIRC the only additional feature the TP-DSL offers in contrast to PDE's containers is the possibility to specify version ranges. Given that this can be implemented from a technical point of view I see no reason to not enhance the syntax of the InstallableUnit container to support version ranges (in a backward compatible manner) there as well.

On the tooling side the Target-Definition Editor already has basic support to search for available IUs but there is room for improvements. But since a target-file uses the XML format I hope it is possible to re-use LemMinX for it. Not because the target-format should be available in other IDEs/Editor (which likely would not make sense) but to re-use its 'infrastructure'. Furthermore I hope this would allow to re-use the LemMinX-Maven tooling in the Target-Editor.
What I dream of, is to have the same tooling support in the Target-Editor's Source tab like in the POM Editor.

This might require some more work, but I'm willing to do it in the future (not sure when I have the time for it).

[mbarbero]

I think @mbarbero might be able to give more insights about future plans for TPD and user-base...

We welcome patches and will provide help to contributors, but this is no trivial task: the DSL has been designed with a single kind of location in mind...

As described in the original bugzilla, tycho should be able to reuse the TPD plugin to first generate a temporary target and then simply read this one...

That would work, but AFAIC remember, Tycho does not want to depend on anything that pulls Xtext...

[mickaelistria]

That would work, but AFAIC remember, Tycho does not want to depend on anything that pulls Xtext...

As long as it's something we can easily remove, it's not too bad.
However I personally believe that the gap between .target and .tpd is getting smaller and smaller and that the remaining effort to make .target include the used features of .tpd is lower than the effort to directly support .tpd in Tycho or PDE, and that improving .target generates much more value; so tpd support doesn't seem so profitable.