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
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