Re: comment-kill and the state of the world

[Ian Zimmerman <bayard@newsguy.com>]

Ian> Ah, but you get the same thing with comment-dwim with an argument
Ian> on a line with an existing comment.  Is that any better?

Stefan> The command throuh which you reach the code is not very
Stefan> relevant.

Ian> I don't understand.  Are you saying people delete comments by hand
Ian> with, say, M-; C-p C-p C-k ?  Or is there some other way I don't
Ian> know about?

Stefan> Looks like I don't understand either.  You complained about a
Stefan> behavior of comment-kill and I replied that I had no idea why
Stefan> the behavior was like that and that I didn't know anybody who
Stefan> used comment-kill.  Then you said "but the same applies to
Stefan> comment-dwim", at which point I tried to clear up the fact that
Stefan> my earlier answer applied to the comment-kill function as much
Stefan> as the command.

So, how _do_ people kill their comments?

Ian> It comes down to comment-dwim.  It really tries to do too much.
Ian> The different situations should be separated, and then common
Ian> patterns will emerge to make into subroutines.

Stefan> Huh?  They are separate.  You can call comment-indent or
Stefan> comment-region or uncomment-region or comment-kill directly.

Ian> Yes.  But comment-dwim does more than just dispatch to them.  If
Ian> you call them directly, you lose the benefit of that additional
Ian> code, whatever it is.

Stefan> The only non-dispatch part of the code is the part that inserts
Stefan> a comment on an empty line.  Are you saying that we should move
Stefan> that code out into its own function?  That'd be fine by me.

I think it should be moved to comment-indent.

Ian> Second, do you have any advice for me when I _want_ them to behave
Ian> the same?

Stefan> Which difference are you referring to ?  Since I have trouble
Stefan> understanding your problems, please try to be very precise and
Stefan> concrete.

Let's say the language's comment delimiters look like this: {- -} .  I
can configure comment-dwim to leave appropriate amount of whitespace and
put the point in the right place, so the situation after an empty
comment is inserted looks like this: {- | -} .  But that won't affect
non-empty lines, because that is handled by comment-indent.  And vice
versa.

Ian> BTW, another bug is that comment-indent uses
Ian> (indent-according-to-mode) to position the comment when
Ian> comment-indent-function returns nil.  That makes no sense when
Ian> there's preceding code on the line

Stefan> Indeed, that's a clear bug.  Does the patch below fix it for you
Stefan> ?

Yes.

Ian> (which is always, now that comment-dwim handles the empty case
Ian> itself).

Stefan> It's not always: comment-indent can still be called directly by
Stefan> the user, and (more importantly), it is called by
Stefan> comment-indent-new-line, i.e. by the auto-fill code.

Ok, good point.

-- 
Wer Schoenheit angeschaut mit Augen, hat dem Tode schon Anheim gegeben.
Von Platen.