Re: skeleton.el _ versus @, a new patch

[Joe Kelsey <joe@zircon.seattle.wa.us>]

On Mon, 2003-04-21 at 17:45, Richard Stallman wrote:
>     > Couldn't you get the same result with the old code
>     > by writing @ _?
> 
>     Here is a patch to add - as an alternate skeleton character.  - operates
>     exactly as _ in setting skeleton-point, but does not interact with the
>     region wrapping effects.
> 
> I don't want to say this is a bad idea, but before we consider it,
> could you possibly tell me the answer to my question?  Is @ in the new
> behavior equivalent to @ _ with the old behavior of @?  If not, could
> someone tell me why not?

The original behavior of @, as coded by Daniel Pfeiffer, was to *only*
set skeleton positions.  The original behavior of _ was twofold: one, to
set skeleton-point (the first occurrence of _ sets skeleton-point), and
two to mark positions for wrapping the skeleton around regions popped
off a stack (actually, the normal region markers).

Stefan added a second behavior for @, to have the first occurrence of
either @ or _ set skeleton-point, the position point goes to after
skeleton insertion.  This new behavior for @ broke the semantics for
skeletons which use _ to set skeleton-point and @ to only set
skeleton-positions.

The behavior I propose adds a new character whose only purpose is to
provide an alternate method to set skeleton-point without interacting
with regions at all.  Therefore, the proposal I have made will set
skeleton-point to the first occurrence of either - or _ while preserving
the original semantics of both @ and _ otherwise.

> Perhaps the "region wrapping effects" make them different--if so, that
> might explain how your answer relates to my question--but I don't know
> if that is true.
> 

The issue Stefan wanted to address was the ability to set skeleton-point
without interacting with the region effects.  Unfortunately, his change
broke the original semantics of @.  It could be argued that it also
broke the original semantics of _, but it is apparantly a benign issue
since _ started with multiple uses and continues with multiple uses
under the new system.  Instead of overloading @ with a new use, we
simply add a new character to take the role Stefan wanted to put on @.

Is this clear enough?

/Joe