[luatex] LuaTeX v1: Two questions from testing
Joseph Wright
joseph.wright at morningstar2.co.uk
Thu Oct 13 11:10:43 CEST 2016
On 13/10/2016 09:51, Hans Hagen wrote:
> On 10/13/2016 8:33 AM, Joseph Wright wrote:
>> Hello,
>>
>> Testing LuaTeX v1, there are relatively few changes from v0.95. However,
>> I've found one logging (?) change and one hyphenation change I didn't
>> expect. With example
>>
>> \hsize 15em
>> This is a supercalifragilisticexpialidocious%
>> \hbox to 1em{}
>> sentence.
>> \tracingall
>> \belowdisplayskip=0pt %
>> $$
>> y = mx + c
>> $$
>> \bye
>>
>> The results are different from pdfTeX in two ways. The empty \hbox does
>> not prevent hyphenation, which it has to-date (so this is not a result
>> of other hyphenation changes). The log also lacks the zero skip after
>> the display.
>>
>> It's not clear to me if either of these changes is deliberate: what's
>> the situation?
>
> The criteria for not hyphenating are somewhat arbitrary esp since
> engines started adding features (literals, whatsits, etc). So, why stop
> at a whatsit that in fact could be a box (ximage) but not at a hbox and
> what about rules (ximages are no longer whatsits but a kind of rule). So
> this is what happens now:
>
> \hyphenationbounds:
>
> 0 : not strict
> 1 : strict start
> 2 : strict end
> 3 : strict start and strict end
>
> So the rules are (i'll add the next info to the manual):
>
> start:
>
> boundary : yes when wordboundary
> hlist : when hyphenationbounds 1 or 3
> vlist : when hyphenationbounds 1 or 3
> rule : when hyphenationbounds 1 or 3
> dir : when hyphenationbounds 1 or 3
> whatsit : when hyphenationbounds 1 or 3
> glue : yes
> math : skipped
> glyph : exhyphenchar (one only) : yes (so no -- ---)
> otherwise : yes
>
> end:
>
> boundary : yes
> glyph : yes when different language
> glue : yes
> penalty : yes
> kern : yes when not italic (for some historic reason)
> hlist : when hyphenationbounds 2 or 3
> vlist : when hyphenationbounds 2 or 3
> rule : when hyphenationbounds 2 or 3
> dir : when hyphenationbounds 2 or 3
> whatsit : when hyphenationbounds 2 or 3
> ins : when hyphenationbounds 2 or 3
> adjust : when hyphenationbounds 2 or 3
>
> So you can decide to default to \hyphenationbounds=3
>
> Hans
Thanks: works as you suggest.
Joseph
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