RE: Minor feature idea

[Drew Adams <drew.adams@oracle.com>]

> In the minibuffer reading a file name, C-a typed within the last
> component could move to the start of that component.  The next time,
> it could move to the beginning of the line.
> 
> If people think it is a good idea, I will write it if no one else
> does.
> 
> Alternatively, C-M-b and C-M-f could move by filename component.
> That is cleaner and does more, but those chars are harder to type
> and users won't come across it in their editing.

It's certainly possible to do such things.  2 cents:

1. The minibuffer is an editing buffer.  The usual commands for
   doing things like this (moving over filename components) should
   apply there as well.

   If there is a lack of such features in general then they can be
   added for the general case, and they would then automatically
   apply to the minibuffer case as well.

2. It should not be assumed that minibuffer input is a single line.

   In my use, for example, there are lots of cases where I yank
   or otherwise retrieve and edit multiple-line text in the
   minibuffer.  Doing this is easier in my context, perhaps
   (Icicles), but it can and should be just as possible in Emacs.

   For my use, both in the minibuffer and outside of it, I bind
   `C-a' and `C-e' to repeatable commands that move to the start
   and end of the previous or next line.  E.g., `C-e' moves to
   the end of the line, repeating it moves to the end of the next
   line, etc.  This helps for multiple-line editing, IMO.

I would prefer that `C-a' and `C-e' remain based on line limits
and not try to move to other-thing limits based on the context.
If they were to be changed to do that, I would prefer that they
at least do so for things that are similar to or analogous to lines.

Similar arguments apply to `C-M-b'/`C-M-f'.  But there I think
you might have a point, in that input that involves filenames
is often distinct from input that involves symbols, and even
when they are both present (e.g. for Lisp sexp input) it is
generally not a problem to use the same keys for both symbols
and filename components.

To repeat what I said in #1: let's add commands/keys that move
forward/backward over filename components, if that is deemed not
easy enough currently.  Let's not co-opt `C-a'/`C-e' for that.

I might not object to `C-M-b'/`C-M-f', but again, why make the
behavior different for the minibuffer?  IOW, maybe they should
handle filename components the same way they handle symbols (?).
On the other hand, it can be handy to use these keys to move
past a whole file name.

[I assume that by "component" you mean whatever is between
(unescaped) `/' chars, or something similar.  I don't know of a
command that does that, but it could be useful.
(`forward-same-syntax' comes close, but it requires repetition
to get across each `/'.)]

Just one opinion, and liable to change.