[luatex] prev field in discretionary nodes
Stephan Hennig
mailing_list at arcor.de
Tue Jan 21 21:01:18 CET 2014
Am 20.01.2014 11:37, schrieb Taco Hoekwater:
> On 19 Jan 2014, at 23:11, Stephan Hennig <mailing_list at arcor.de> wrote:
>
>> Is reusing node lists in general safe?
>
> Assuming you are certain that there are no internal TeX references
> to that node list left after your manipulation. Otherwise no.
What about the nodes pointed to by first prev fields in discretionary
nodes? Can discretionary nodes be safely removed from a list or can
that break something due to the internal references described in your
other mail?
>> Why do you better use node.insert_before/after even when
>> not changing head? …
>
> Because it is easy to forget a prev or next, but also because
> insert_before / insert_after actually check that prev and next
> are valid (active) nodes.
And they set-up prev fields in sub-lists of discretionary nodes, which
cannot be done manually. Are there any other such nodes that /require/
the use of insert_before/after?
Best regards,
Stephan Hennig
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