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RE: [cdt-dev] First gotcha with add/exclude children of FFS

We've been working on Eclipse/CDT based products for about three years now.  I'm sorry to say that the project model is still not satisfactory for our purposes.  We've tried many angles, but are still stuck with some pretty serious limitations.  I've volunteered to investigate the EFS route to see if it will help at all.  Based on this thread I'm assuming it won't.
 
Let me give you a brief overview of how our users work, and then discuss the problem we've run into.  I don't think any of this is specific to our users BTW.
 
Most of our users have existing code bases.  They simply want to "import" it into the IDE.  Others will create new projects from our templates.  The new projects are created in the workspace.  Imported projects could be anywhere in the file system.  Often times they will import several projects from the same source tree.  This is where our biggest problem is.  Let's say the source base looks like this:
 
C:\MyProjects\Project1\...
C:\MyProjects\Project2\...
C:\MyProjects\Common\...
 
Because both projects share code in the Common directory, the logical root project directory for both Project1 and Project 2 is C:\MyProjects\.  But in Eclipse you can't have two projects with the same root.  This is where the .project and .cproject files are created.  So currently our users would import Project1 with the natural root (C:\MyProjects\), but Project2 has to be rooted at C:\MyProjects\Project2\.  This means that any source/headers from the common directory are not under Project2.  This means those files are not in the project explorer for that project, are not indexed, etc..  We logged this against the platform - https://bugs.eclipse.org/bugs/show_bug.cgi?id=78438.  Basically if you put the .project file anywhere, but have a project root attribute, this would cease to be a problem.
 
Our first product actually always created the .project in the workspace, and for imported projects, would create links to files and folders.  We ran into so many issues with this that we had to change the model.  I don't recall all of the issues, but here's a list of some:
 
- Version control simply didn't work at all
 
- You can't make file system changes with links.  For example, if you want to rename a file or folder, or move a file around, you can't do this with linked resources.  It only changes the link itself, not the underlying resource.
 
- Creating new resources in a project with links is confusing at best.  Let's say you have a project with a linked folder and file at the root.  If you create a new file or folder at the root, it is created in the workspace, not where the other folder/file are in the file system.  But if you create a new file under the linked folder, it gets created where you'd expect.
 
- The location of the .project/.cproject files are problematic.  Some users will want to keep these in version control, while others won't.  Those that do want them created in the source tree, but those that don't want them elsewhere, like the workspace.  I forget now why this was a problem with linked resources, but there was something weird going on there.
 
I suppose it's worth noting that the last time we really looked at this was in Eclipse 3.2, so some of this may have been fixed by now.  But I doubt it.  In general linked resources are second class citizens.  Some IResource API's just don't work for linked resources.  Just search for references to IResource#isLinked for "special handling".  I suspect that we'll run into similar issues with EFS though - see getLocation vs getLocationURI.
 
We also have the same issue that Doug is trying to address (hiding some branches in a source tree).  This is much less of an issue for us though.  You can already reduce the scope of the indexer and the build.  The only real issue for us is for a very large source tree, you're going to get IResource's for everything, which slows things down quite a bit.  There is actually somewhat of a problem in reducing the indexer scope - see https://bugs.eclipse.org/bugs/show_bug.cgi?id=178159.
 
The hidden attribute addition sounds promising for hiding resources under the project root, but doesn't really do anything to add flexibility to the contents of a project.  EFS sounds like it would though.  What I mean by that is, having resources under a project that are real resources, not linked, but that don't live under the project root in the file system.  I've just started looking into EFS, so maybe it's a bit of wishful thinking at this point, but I'm hoping we could create a project anywhere, and when we create it we pass the URI location from our own EFS.  Then when asked for the children, we could return URI's for files from anywhere in the file system, or on other machines even.  This would seem to hold the potential for working around the issues listed above.  We'd basically have an EFS map from what we want under a project to the actual file system.
 
So hopefully some of the experts can chime in here.  Is my hope for EFS unrealistic?  Is there a different approach we should look at?
 
Thanks,
Warren
 


From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of ext Brunauer, Walter
Sent: Friday, January 25, 2008 1:47 AM
To: CDT General developers list.
Subject: RE: [cdt-dev] First gotcha with add/exclude children of FFS

Hi,
 
after reading this rather long thread, I'll decided to throw in my personal opinion.
 
I consider this approach to work against one of the most general Eclipse platform paradigms, where a project is defined to be a root directory and everything in it. IMO, the more workarounds are introduced against this paradigm, the more problems will be faced, and the more incompatibilities (or at least unawarenesses) created.
 
Isn't the whole problem you try to solve here rather about what files should go into the build (and probably into the indexer) than what files are part of a project? I understand that CDT has no separation of what a project and what the build input is (well, IIRC one can exclude specific files from the build, but in general, the project content defines the build input, right?).
 
In our commercial IDE, we separated this. This not only introduced much more powerful build setup capabilities in general, but especially enabled users to setup build artifacts with arbitrary contents (think of sources being compilable with different compiler flags for different build artifacts, build input exclusion patterns, build input from all over the workspace, multiple build artifacts within the same project, reusable build artifacts accross project boundaries, etc., etc., etc.). BTW, we call this build system flexible managed build - because that's what it is:-)
 
Of course, one can setup CDT projects as of today to exactly contain what is desired (with the help of linked resources). However, I find linked resources to be cumbersome and error prone, though many of our customers start out with them during evaluation as well, mostly because they are looking for a way to achieve what they did in the past with other non-Eclipse based IDEs, but sooner or later I know of lots of them realizing its much easier to use the features of our flexible build system instead, especially if projects need to be shared in a team. And now think of virtual file systems, the potential complexity of these, hidden assumptions, restrictions, etc. Sounds worse than linked resources to me.
 
I guess, the point I am trying to make is: whatever you decide to do, make it understandable and transparent (and of course as simple as possible to use) for the user.
 
As said, just my 2 cents,
 
Walter


From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Schaefer, Doug
Sent: Donnerstag, 24. Jänner 2008 23:17
To: CDT General developers list.
Subject: RE: [cdt-dev] First gotcha with add/exclude children of FFS

Jogging through the code, it really looks like the HIDDEN feature is what I was looking for. What I haven't found yet is UI to make a resource hidden or a navigator filter to show hidden resources (in case you want to bring them back). Is this planned?
 
Assuming we have the core features available to link in and hide resource, I think we still have workflow issues that need to be addressed. I like Ken's idea of a file that controls the linking/hiding. We could have an import/export mechanism for setting up projects based on this file. A nice wizard for creating the file would also be good, similar to the way the way the export file system wizard works.
 
Given this, we may be further along than we thought (BTW, the hidden stuff seems to have been added in 3.4 M4).
 
Cheers,
Doug


From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Schaefer, Doug
Sent: Thursday, January 24, 2008 2:51 PM
To: CDT General developers list.
Subject: RE: [cdt-dev] First gotcha with add/exclude children of FFS

Thanks Michael/Szymon,
 
Is there a bug describing the isHidden feature?

Doug


From: cdt-dev-bounces@xxxxxxxxxxx [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Michael Valenta
Sent: Thursday, January 24, 2008 11:37 AM
To: cdt-dev@xxxxxxxxxxx
Subject: RE: [cdt-dev] First gotcha with add/exclude children of FFS

Doug et al,

Szymon is really the person you want to bug on this but I'll throw in my 2 cents ;-)  First, I have to say that a solution at the IResource level (e.g. using linked resources and the new hidden folder support) is infinitely better from a repository provider perspective than an EFS based solution.  You may not get all the Team support you want at the IResource level but a solution at the EFS level would certainly break the existing CVS client since the CVS client isn't EFS aware to any great extent. For instance, if you tried to hide a folder using EFS, the CVS client would probably try and recreate it the next time you performed a Team>Update. It is also important to note that the Platform does not provide all the hooks required by repository providers and I know of at least one provider that has resorted to using it's own EFS implementation under projects that are mapped to that provider to get the capabilities it requires. I think it is important that tooling in Eclipse stick to using the IResource layer as the layer they operate on and let the repository provider (or any other tooling whose responsibility it is to manage the available files) control the underlying file system. If there are shortcomings or enhancements required then you should push to get them in at the IResource level.

As for the current state of Team support for linked resources, I think the best approach is to enumerate some specific scenarios of how you see linked resources and exclusions working with descriptions of what you need to do today to get Team support and what you would like to see. It is also important to know if you expect all the links to come from the same repository (or at least repository type) or whether a project could contain content from different repository types (obviously the later would be more difficult to accommodate than the former).

Hope this helps,
Michael