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bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point
From: |
Drew Adams |
Subject: |
bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point |
Date: |
Mon, 27 Feb 2017 12:35:46 -0800 (PST) |
> > 2. The purpose of `rectangle--pos-cols', just as was the purpose
> > of the previous (Emacs 24.5) code, is to return the rectangle
> > columns. Nothing more. Its purpose is not to move point and
> > leave it in some other place that is not a rectangle corner.
>
> The code you extracted in 24.5 is (modulo a few dropped lines)
>
> (save-excursion
> (goto-char start)
> (setq startcol (current-column))
> (beginning-of-line)
> (setq startpt (point)) ;; [dropped in modeline-posn]
> (goto-char end)
> (setq endcol (current-column))
> (forward-line 1) ;; [dropped in modeline-posn]
> (setq endpt (point-marker)) ;; [dropped in modeline-posn]
> ;; ensure the start column is the left one.
> (if (< endcol startcol)
> (let ((col startcol))
> (setq startcol endcol endcol col)))
>
> The equivalent in 25.1 is
>
> (save-excursion
> (let* ((cols (rectangle--pos-cols start end))
> (startcol (car cols))
> (endcol (cdr cols))
>
> But for some reason you don't want to extract the
> save-excursion from 25.1.
You still don't understand, it seems. The workaround for my
code is obvious, and I have made it: wrapped each call to
`rectangle--pos-cols' in `save-excursion'.
The point of filing the bug is to help Emacs, not my code.
I wanted you to be able to test to repro the bug using my
code before adding a `save-excursion' wrapper.
Clearly I have to add such a wrapper anyway, since my library
needs to support Emacs 25.1 (in addition to 22-24). A fix of
`rectangle--pos-cols' for Emacs 25.2 or later would not let me
avoid wrapping with `save-excursion'. It cannot possibly be
for the benefit of my code that this bug gets fixed or that I
filed the bug.
Clearly I think that this function should clean up after
itself, using `save-excursion'. Its _only_ purpose, AFAICT,
is its return value, not (also) the side effect of leaving
point somewhere other than at the rectangle corner.
Clearly you disagree about that - that it should clean up
after itself. Do you also think that it is important that
it leave point at a new location? Is there a reason that
it _should_ have that side effect, and not simply return
the proper value?
> > 3. `rectangle--pos-cols' is a general function. It should not
> > be considered internal. It is useful generally - I have
> > reused it, as one example. (I have not used `apply-on-rectangle'.)
> >
> > Is there a reason to have `rectangle--pos-cols' move point,
> > instead of use `save-excursion'?
>
> I don't want to add unneeded clutter.
What you call "unneeded" and "clutter" I call normal and clean.
What you call uncluttered code I call irresponsible code. We
will, I guess, just have to agree to disagree about this.
> > What's the argument in
> > favor of not having this code be as clean as it was in Emacs
> > 24.5? Why favor this regression?
>
> It's clearly not a regression.
Not if code calls only `apply-on-rectangle', no.
Apparently you don't think that `rectangle--pos-cols' is (or
could be, if the bug were fixed) a useful general function.
That's OK. Users will just roll their own. I think we can
end this discussion now - feel free to close it as wont-fix.
Thanks for spending time looking into it, anyway (sincerely).
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/17
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/19
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, npostavs, 2017/02/26
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, npostavs, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Noam Postavsky, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Noam Postavsky, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point,
Drew Adams <=
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, npostavs, 2017/02/27
- bug#25777: 25.1; [PATCH] `rectangle--pos-cols' should not move point, Drew Adams, 2017/02/28