AW: Recursive externals checkout

Hi, Dominik,

Von: Dominik Psenner [mailto:dpsenner_at_gmail.com]
> >http://tortoisesvn.tigris.org/ds/viewMessage.do?dsForumId=4061&dsMessageId=2939615
> >>
> >> Do you think svn checkout should be defensive against recursive externals?
> >
> >At elego (where I work) we actually use this as a trick question during
> >Subversion workshops. People who don't necessarily know about externals
> >are asked to check out a working copy (which, unknown to them, contains
> >recursive externals) and are asked to figure out if anything is going
> >wrong and if so how to fix it. Once they've figured out and fixed the
> >problem they understand what externals are :)
> >
> >That aside, I wouldn't mind if svn printed a warning or error message
> >when it finds a recursive externals definition. But off-hand I don't
> >what a good method for detecting recursion would be.
> >It's somewhat complicated by the fact that externals are currently
> >separate working copies and that the recursion might be rooted not only
> >at the immediate parent WC but at some parent of the parent.
> >Cross-working-copy operations aren't trivial to implement correctly.
>
> The problem may be levered by recursively comparing the repository UID and
> the relative path in the uri when the external is resolved. Proofing that
> this check would be enough is left to the reader. :-)

This will catch the "simple" case when an external includes its own parent directory.

But it will not catch mutually recursive externals (svn://path/to/a/ includes svn://path/to/b/ and vice-versa), there might even exist cycles over 3 or more repositories...

Best regards

Markus Schaber

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