emacs and SUBST command

emacs and SUBST command

[Mickey Ferguson]

I've discovered that in the SUBST command, one can use not only a letter but a number for a drive designator.  For example, you can use

    SUBST t: C:\Temp

which is the usual and familiar way.  However, one can also use

    SUBST 1: C:\Temp

Both are valid.  However, within emacs if I try to reference a file that's in C:\Temp, say, C:\Temp\Myfile.txt, by using the 1:\Myfile.txt notation, emacs doesn't find the file.  It can't work with anything under the 1: "drive".  Additionally, if my current drive is set to 1: and I try to start emacs, it crashes.

I'm currently using emacs 21.3.1 on XP SP2.  Is this something that's fixed in 22.x, the current version, or is this simply something the authors weren't aware of and/or didn't anticipate?

Re: emacs and SUBST command

[Stefan Monnier]

> Both are valid.  However, within emacs if I try to reference a file that's
> in C:\Temp, say, C:\Temp\Myfile.txt, by using the 1:\Myfile.txt notation,
> emacs doesn't find the file.  It can't work with anything under the 1:
> "drive".  Additionally, if my current drive is set to 1: and I try to
> start emacs, it crashes.

> I'm currently using emacs 21.3.1 on XP SP2.  Is this something that's
> fixed in 22.x, the current version, or is this simply something the
> authors weren't aware of and/or didn't anticipate?

IIRC all the code that tries to handle DOS drive letters looks for something
like "[a-z]:", so it's probably still there.  Please report this problem via
M-x report-emacs-bug.

This said, I'm not sure if a fix is a good idea (when you enter a file such
as "/foo/a:/bar", Emacs automatically turns it into a:/bar, which is usually
a convenient feature, but can be inconvenient in case you have a directory
called "a:", so the more permissive we get w.r.t. recognizing a "drive
letter prefix" the more often this inconvenience risks showing up).


        Stefan


PS: I have no idea what `subst' does and rarely if ever use Windows.

Re: emacs and SUBST command

[Eli Zaretskii]

> Date: Thu, 9 Aug 2007 11:05:54 -0700
> From: "Mickey Ferguson" <MFerguson@plantcml.com>
> 
>     SUBST t: C:\Temp
> 
> which is the usual and familiar way.  However, one can also use
> 
>     SUBST 1: C:\Temp
> 
> Both are valid.  However, within emacs if I try to reference a file that's in C:\Temp, say, C:\Temp\Myfile.txt, by using the 1:\Myfile.txt notation, emacs doesn't find the file.  It can't work with anything under the 1: "drive".

Emacs deliberately doesn't support this functionality.  It only
supports drive letters A-Z.  Supporting other characters would be a
real PITA, since remote file names and files in archives also use
colons.

Can you tell where this is a real problem?