[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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