Re: file-relative-name and remote files

[Lars Hansen]

> IMHO, the following might work: file-relative-name finds a filename 
> handler for the filename and one for the directory. If they are 
> different, then the two must come from different handlers, so do like 
> the different-drives case. If they are equal, invoke the handler. This 
> requires a new file operation, file-relative-name. It seems to work 
> for Ange-FTP and Tramp. However... Imagine that there was a filename 
> handler which could look inside of tar files, so that the filename 
> /tmp/foo.tar/x/y would extract the file x/y from the tarball 
> /tmp/foo.tar. So should (file-relative-name "/tmp/foo.tar/x/y" "/tmp") 
> eval to "foo.tar/x/y" or not?


What about changing it to:
file-relative-name finds a filename handler for the filename and one for 
the directory. If they are non-nil and different, then the two must come 
from different handlers, so do like the different-drives case. If they 
are non-nil and equal, or one is non-nil and the other nil, invoke the 
handler. If both are nil, execute the build in code.

Then the handler can decide what to do when one of the files is an 
ordinary one, and in your example it could return "foo.tar/x/y".