On Fri, Nov 05, 2010 at 03:22:06PM +0200, Khaled Hosny wrote:
On Fri, Nov 05, 2010 at 01:59:54PM +0100, Manuel Pégourié-Gonnard wrote:
Hi,
Sorry if this is very clear from the manual, maybe I just didn't read the part where it is explained (or I read it but was too stupid/tired to notice), but I don't understand the meaning of the return value of some callbacks.
The first example (by order of apparition in the manual) is pre_linebreak_filter, whose calling convention is:
function(<node> head, <string> groupcode) return true | false | <node> newhead end
I think it's clear what returning a newhead node does, but I don't understand what returning true or false means for this callback. Other similar callbacks include post_linebreak_filter, (h|v)pack_filter, pre_output_filter, etc.
I think it is explained in section 4.1:
For some minor speed gain, you can assign the boolean false to the non-file related callbacks, doing so will prevent LuaTeX from executing whatever it would execute by default (when no callback function is registered at all). Be warned: this may cause all sorts of grief unless you know exactly what you are doing! This functionality is present since version 0.38.
Not sure about "true" though.
Please ignore this, I just confused things up. Regards, Khaled -- Khaled Hosny Arabic localiser and member of Arabeyes.org team Free font developer