file-remote-p

file-remote-p

[Michael Albinus]

Hello,

file-remote-p checks for a file name handler of the argument, and
returns the value of the property file-remote-p of that handler.

That doesn't work in some cases.

(file-remote-p "/ssh:localhost:/file.gz") returns nil, because the
first file name handler which is found is jka-compr-handler.

(file-remote-p "/ssh:local") also returns nil, because the handler in
question is tramp-completion-file-name-handler, lacking the
file-remote-p property as well.

There are (at least) 2 ways to solve the problem:

1. file-remote-p loops looking for a file name handler. If the handler
   which is returned doesn't have the file-remote-p property, that
   handler is inhibited, and the next handler is requested. Either
   until a handler with file-remote-p property is found, or no other
   handler is found.

2. file-remote-p is implemented in the respective file name handlers
   just returning t (tramp-file-name-handler; ange-ftp-hook-function
   isn't active in file-name-handler-alist any longer). If other file
   name handlers are passed for file-remote-p, they do inhibit
   themselves, and apply the operation, again.

I tend to prefer alternative 2. An implementation of file-remote-p in
Tramp (and maybe other packages I don't know) would be simple. The
patch in files.el would look like this:

--- files.el    27 May 2004 20:23:31 -0000      1.697
+++ files.el    28 May 2004 19:34:42 -0000
@@ -642,9 +642,10 @@
 
 (defun file-remote-p (file)
   "Test whether FILE specifies a location on a remote system."
-  (let ((handler (find-file-name-handler file 'file-local-copy)))
+  (let ((handler (find-file-name-handler file 'file-remote-p)))
     (if handler
-       (get handler 'file-remote-p))))
+       (funcall handler 'file-remote-p file)
+      nil)))
 
 (defun file-local-copy (file)
   "Copy the file FILE into a temporary file on this machine.

What do people think about?

Best regards, Michael.

Re: file-remote-p

[Stefan Monnier]

> I tend to prefer alternative 2. An implementation of file-remote-p in
> Tramp (and maybe other packages I don't know) would be simple.
[...]
> What do people think about?

I obviously completely agree since I pointed out something similar back when
file-remote-p was introduced (although I probably wasn't as clear as you
were: I just intuited that it wouldn't be flexible enough, although I was
thinking of cases like url-handler-mode where file:///foo/bar should be
considered local).


        Stefan

Re: file-remote-p

[Richard Stallman]

Since the simple solution I tried does not work, let's use your method
2, which is general and follows the way other operations work.