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Re: suspected bug report or feature request - tagging a sparse directory

From: Stas Cherkassky <scherkas_at_gmail.com>
Date: Thu, 14 Jan 2010 13:00:07 +0200

Julian,

thanks you for your reply.
Your approach may technically work, but, I am afraid, it's not realistic in
real large project.

The [everything except dirA and dirB] part may be quite complicated for
large sparse tree.

The second approach (multiple svn cp WC URL) is also cumbersome and requires
multiple commits.
It also won't work if some files were already tagged before (you can't svn
cp over existing file).

Both approaches are not easy to automate (too many cases to consider).
Just consider, what will happen 2nd time, when user B wants to update the
tag in his WC. Some files were tagged before, some - not. They may be in
the same dir, deep inside the tree.

Just compare it to 'cvs tag -R -F tagX myproj'. The -F switch would tag
untagged files, and move tag on tagged files. Whatever files I have in my
WC. In one simple command.

You may point our (correctly) that this feature was not requested or was not
considered important enough - after all it's open source community, and
developers do what they think is important and interesting to them. And
this is all correct. Incorrect is to claim that SVN does have the ability.
Even if it technically does, its absolutely unusable (all IMHO, of course).
The only real solution that I can see, it to have some switch for 'svn cp'
that will do exactly what's needed - including override files already under
the ^/tags/ dir..

thanks,
Stas

On Wed, Jan 13, 2010 at 8:00 PM, Julian Foad <julianfoad_at_btopenworld.com>wrote:

> Hi Stas.
>
> Your question raises an important issue: "What are the semantics of
> sparse directories?" You expected "svn copy" to copy just the parts that
> are present in the WC, whereas in fact it copies the whole logical tree.
> There is a reason for that, but I think it is not clear how a user
> should expect each Subversion command to behave.
>
> In this email I will just address how it works at the moment and how to
> achieve the tagging that you wanted. I will start a separate email
> thread to discuss the semantics of sparse directories.
>
>
> Stas Cherkassky wrote:
> > I don't want to remove parts of the tree from the repository.
> > What I want is, effectively, a way to independently mark separate
> > parts of the tree with the same tag.
> > (I tried to explain it in my example). I don't see how your method
> > (using svn rm) does it.
>
> I'll explain my method using "svn rm" first, and then the method using
> "svn copy" with multiple source arguments.
>
> You don't exactly want to remove parts from the repository, but one way
> of thinking about what you want to create in the repository (the tagged
> data) is a copy of your normal working tree except with some parts
> removed. A common and flexible way to create a tree in a Subversion
> repository is to create it in a WC and then commit (or in this case
> copy) it. That's what my suggestion was for.
>
> More precisely,
>
> svn rm myproj/[everything except dirA and dirB]
> svn copy myproj ^/tags/rel_X/
>
> And then if you want to restore your WC to how it was, you can revert
> the parts that are scheduled for deletion:
>
> svn revert -R myproj/[everything except dirA and dirB]
>
>
> Another way of thinking about the task is to ask Subversion to copy only
> the parts you want:
>
> $ svn copy --parents myproj/dirA myproj/dirB ^/tags/rel_X/myproj/
> Committed revision 2.
>
> $ svn log -vq -c2
> ------------------------------------------------------------------
> r2 | julianfoad | 2010-01-08 10:37:34 +0000 (Fri, 08 Jan 2010)
> Changed paths:
> A /tags/rel_X/myproj
> A /tags/rel_X/myproj/dirA (from /myproj/dirA:1)
> A /tags/rel_X/myproj/dirB (from /myproj/dirB:1)
> ------------------------------------------------------------------
>
> There is a limitation with this form of the copy command. With a single
> "svn copy" command, all the specified source objects (dirA and dirB in
> this case) are created as direct children of the target directory. There
> is no way to extend that example to make myproj/dirC/foo go to
> ^/tags/rel_X/myproj/dirC/foo at the same time as copying dirA and dirB.
> However, you can extend a tag by making a further commit to it with a
> second copy command, unless committing to a tag is disabled in your
> repository. So you could do:
>
> $ svn mkdir ^/tags/rel_X/myproj -m "New tag. Incomplete."
> $ svn copy dirA ^/tags/rel_X/myproj/ -m "Incomplete."
> $ svn copy dirB ^/tags/rel_X/myproj/ -m "Incomplete."
> $ svn copy --parents dirC/foo ^/tags/rel_X/myproj/dirC/foo
> -m "Completed tag for rel_X of myproj."
>
>
> > If a tag is a property of a file (like in CVS), it's natural operation :
> > cvs tag -R dirA -t relX # tags whatever files and versions I have in
> WC
> > and then
> > cvs tag -R dirB -t relX
> > In the end I have both dirA and dirB tagged with same tag relX.
>
> You can certainly do the equivalent thing in Subversion: it is the "svn
> copy" method that I described above.
>
> > If a tag is an object (like in Perforce), and it's property is a list
> > of files/versions it applies to, it's also easily achievable in very
> > similar manner - 2nd p4 tag call would just add more files to that
> > property of the tag object.
>
> That is also like the "svn copy" method that I described above.
>
> > With SVN's implementation of tags (logical directory in repo), it
> > would also be possible, had 'svn copy' behave like I suggested.
>
> That is true.
>
> > IMHO, this way is more intuitive - that's what unix copy command would
> do.
>
> The Unix copy command is not a fair comparison, because a normal Unix
> directory is not a temporary working representation of the real data
> stored on the server, and so does not have a way to mark certain files
> and directories as "excluded from the local working copy". Or, looking
> at it another way, if you mark some of the directory's children as
> hidden (by renaming them to start with a dot in Unix), then a copy of
> the whole directory will still include those hidden items.
>
>
> - Julian
>
>
>

-- 
Stas Cherkassky
email:   scherkas_at_gmail.com
phone:  +972-54-4261959
Received on 2010-01-14 12:00:42 CET

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