Re: "Text is read-only"... except it isn't... or shouldn't be

[Kevin Rodgers]

On 5/14/13 2:39 PM, ken wrote:
> On 05/14/2013 09:39 AM Eli Zaretskii wrote:
> > > Date: Tue, 14 May 2013 08:22:00 -0400
> > > From: ken <gebser@mousecar.com>
> > > CC: Eli Zaretskii <eliz@gnu.org>, help-gnu-emacs@gnu.org
> > >
> > > [...] overly simplistic strategy for determining a file type merely
> > > by looking at the filename extension, especially when this can be
> > > more suitably and accurately and intelligently accomplished by
> > > determining a file's magic number as the Linux "file" utility does.
> >
> > Emacs does look at the magic signature, see magic-mode-alist.
>
> They why didn't it see that my file was (obviously) a text file and not an image
> file?

1. Because the default value of magic-mode-alist is nil.

2. Because the default value of auto-mode-alist matches the ".gif" extension.

3. Because it is not obvious what the signature is for a text file -- perhaps
   something like "\\`[[:print:]\t\f\r\n]", which is so general that it would
   prevent most of the existing automatic method from working.

See the "Choosing Modes" section of the Emacs manual.

--
Kevin Rodgers
Denver, Colorado, USA