bug#20871: 25.0.50; fill-single-char-nobreak-p does not recognize a single-letter word when it is preceded by an open paren

[Michal Nazarewicz <mina86@mina86.com>]

On Sun, Apr 17 2016, Eli Zaretskii wrote:
> Could you please elaborate on the bug itself?
>
> See, the function in question, fill-single-char-nobreak-p, is
> documented as a possible value to use in the fill hook, for a very
> specific purpose.  If you are saying that it doesn't fulfill that
> purpose well enough, please show a use case where it fails to do that.
> At least the situation you described, with " (a", doesn't seem to fit
> the use cases which this function is supposed to cover, since the
> parenthesis makes a 2-character sequence, whereas
> fill-single-char-nobreak-p aims to support isolated one-character
> words.

As person who wrote ‘fill-single-char-nobreak-p’ I can say that its
intention was to work for Polish and Czech typography.  In other words,
what Marcin reported is a genuine defect in the function.

In particular, function’s documentation mentions *one-letter* sequences,
not *one-character* sequences:

	Return non-nil if a one-letter word is before point.

(Admittedly, the name of the function is misleading).

As such, I would suggest applying the fix to
‘fill-single-char-nobreak-p’ rather than introducing a new function.

(And perhaps adding an alias and deprecating the old name if misleading
name is too big of a problem).

As another point of context, ideally, ‘tildify-mode’ and
‘fill-single-char-nobreak-p’ would use the exact same logic since they
both work to address the same underlying typographic conventions.

-- 
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»