bug#21072: Brave new mark-defun (and a testing tool)

[Marcin Borkowski <mbork@mbork.pl>]

Hey,

and thanks for your feedback!

My answers to particular points are below.


On 2017-04-03, at 00:56, npostavs@users.sourceforge.net wrote:

> Marcin Borkowski <mbork@mbork.pl> writes:
>
>>
>> OK, I pushed the branch "fix-bug-21072".  Can anyone confirm that it's
>> ok and either merge it into master or tell me that I can do it?
>
>>  \f
>> +** New macro 'elisp-tests-with-temp-buffer'
>> +which helps writing tests for functions that should change buffers in
>> +specific ways or manipulate point or mark positions.
>> +
>> +---
>
> I don't this should be documented in NEWS since the macro is being added
> to a test file, so it's not part of Emacs' libraries.  Also, the format
> of the NEWS entry is wrong in the same way as the next one (see below).

I deleted that from etc/NEWS.

>> +With a prefix argument, it marks that many defuns or extends the
>> +region by the appropriate number of defuns.  With negative prefix
>> +argument it marks defuns in the opposite direction and also changes
>> +the direction of selecting for subsequent uses of @code{mark-defun}.
>
> This doesn't say what exactly happens with zero as argument.  The code
> seems to do something odd.  Perhaps it should just be a user-error
> instead?  Or maybe just a nop.

Good catch.  I guess a no-op is fine.

>> modified   etc/NEWS
>> @@ -363,6 +363,15 @@ words where first character is upper rather than title case, e.g.,
>>  "DŽungla" instead of "Džungla".
>>
>>  \f
>> +** New behavior of 'mark-defun' implemented
>> +Prefix argument selects that many (or that many more) defuns.
>> +Negative prefix arg flips the direction of selection.  Also,
>> +'mark-defun' between defuns correctly selects N following defuns (or
>> +-N previous for negative arguments).  Finally, comments preceding the
>> +defun are selected unless they are separated from the defun by a blank
>> +line.
>> +
>> ++++
>> * Changes in Specialized Modes and Packages in Emacs 26.1
>>
>
> This entry should go before the page separator, and the "+++" should go
> on the line just above the entry, not after it.

That one I do not understand.  This means that "+++" goes essentially
_to the previous entry_, which doesn't seem to make sense (especially
when viewing NEWS folded, which I assume everyone does, right?).

>> +(defun beginning-of-defun-comments (&optional arg)
>
>> +  (let (nbobp)
>> +    (while (progn
>> +             (setq nbobp (zerop (forward-line -1)))
>> +             (and (not (looking-at "^\\s-*$"))
>> +                  (beginning-of-defun--in-emptyish-line-p)
>> +                  nbobp)))
>> +    (when nbobp
>> +      (forward-line 1))))
>
>
> The looking-at call is redundant, right?  Anyway, can't that all be

Hm.  Probably yes, although this seems to be not very well documented in
`forward-comment's docs.

> replaced by just
>
>     (forward-comment (- (point)))
>     (unless (bolp)
>       (forward-line 1))

My tests say no.  Consider these contents of a buffer:

--8<---------------cut here---------------start------------->8---
;; Comment at the bob

(defun func (arg)
  "docstring"
  body)
--8<---------------cut here---------------end--------------->8---

Put the point inside the defun and call mark-defun.  Your version marks
the comment at the beginning, mine doesn't.

>> +(defun mark-defun (&optional arg)
>
>> +  (let (nbobp)
>> +    (while (progn
>> +             (setq nbobp (zerop (forward-line -1)))
>> +             (and (looking-at "^\\s-*$")
>> +                  nbobp)))
>> +    (when nbobp
>> +      (forward-line 1))))
>
> I think this can be just
>
>     (skip-chars-backward "[:space:]\n")
>     (unless (bolp)
>       (forward-line 1))

This OTOH does pass my tests, though I guess it would be clearer to
replace (bolp) with (bobp) in the above code (if I understand correctly,
in this situation they should be equivalent).  WDYT?

Thanks a lot,

--
Marcin Borkowski