Re: Processing a file that may already be open

[Sean McAfee <eefacm@gmail.com>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> (defmacro with-visited-file (path &rest body)
[...]

> - use make-symbol rather than gensym: it's faster, doesn't pollute the
>   global symbol table (aka obarray), and doesn't rely on CL.

gensym is just a thin wrapper around make-symbol; how could it pollute
the global symbol table?

I usually prefer gensym because I don't like to be obliged to give the
new symbol a name.  I don't care what it's named.  And I don't mind
relying on CL.  It's the closest I get to being able to use Common Lisp
on a regular basis.

> - avoid evaluating "file" multiple times (in case the caller does
>   (with-visited-file (setq foo (concat foo ".el")) blabla))

Good point.

> - avoid find-file: find-file is a user-level command, Elisp code should
>   use find-file-noselect instead.  find-file will call switch-to-buffer
>   to display the buffer, which can fail or pop up a new window or a new
>   frame, none of which we want to see happen here.

Also a good point.  Thanks.

There's still a few minor issues to be worked out, though.  Like, should
I save the buffer after editing it?  Obviously yes, if the buffer didn't
exist before.  But if any buffers were already visiting the file, I
should probably only save it if none of them have been modified since
the file was last saved.