auto-save-file-name-transforms too simple?

[Kai Großjohann]

I just discovered the variable auto-save-file-name-transforms.  I
like the idea behind it, but I'm a little bit concerned the whole
thing might be too simple minded.

For one thing, the default value is set up to put some auto-save
files in the /tmp directory.  This will fail on systems where /tmp
does not exist, I think.  Can we expect all systems to have that
directory?  What about Windows and MacOS?

Secondly, the documentation for the variable says that it wants to do
things with remote files, but it depends on the concrete filename
syntax for remote files.  Wouldn't it be better to find out if the
files are remote rather than blindly assume that the ange-ftp
filename syntax won't change and that no other files are remote?

A small improvement might be to change ange-ftp so that it adds an
entry to the variable.  Then ange-ftp can control what regexp to use,
so the ange-ftp maintainer will make sure that it's always the right
one.  (The default value for auto-save-file-name-transforms would
then be nil, I guess.)  Is it considered okay for packages to do such
things when they are loaded?

Another issue is that the auto-save files for two files named
"Makefile" will clobber each other.

Another issue is that auto-save won't work when editing a remote file
foo, but /tmp/foo already exists and isn't writable by the user
running Emacs.  So if I know that Joe likes to edit files named foo,
then I can play a trick on him by creating the file /tmp/foo which he
can't write.

I didn't really try all this, I just read the documentation for the
variable.  Sorry if this has lead to wrong conclusions.

kai
-- 
Simplification good!  Oversimplification bad!  (Larry Wall)