Re: writebetweenlist regression (mkiv)

[Marco Pessotto <melmothx@gmail.com>]

Hans Hagen <pragma@wxs.nl> writes:

> On 13-12-2010 11:20, Steffen Wolfrum wrote:
>>
>> Am 08.11.2010 um 23:03 schrieb Marco:
>>
>>>
>>> Hello there.
>>>
>>> Currently \writebetweenlist doesn't work as advised. It inserts the
>>> argument before the last entry of the list. The minimal example is
>>> provided by the reference itself.
>>>
>>> http://wiki.contextgarden.net/Reference/en/writebetweenlist
>>>
>>> The rule is correctly inserted at http://live.contextgarden.net/ and in
>>> the ConTeXt shipped with TeXlive 2010 (2010.05.24), but not with the
>>> current beta and the 2010.07.30 version. mkii works fine.
>>>
>>> It prints
>>>
>>> --rule--
>>> List entry A
>>> List entry B
>>
>> Unfortunately, I can confirm this with current version:
>>
>> ver: 2010.12.12 17:06 MKIV
>>
>> Help please!
>
> There is a good reason for this. Inbetween has multiple usage and
> these are conflicting:
>
> - in order to get the right page info associated it needs to be
> anchored in the text stream
> - in that case a node can interfere with spacing and can come unexpected
> - sometimes direct flushing is needed, sometimes delayed
>
> btw, all these issues have been observed by users every now and then
>
> Now, if unexpected interference is the hardest to track down,
> inbetween is an immediate action. In principle one can influence that
> but it's not that intuitive. So, I've now added an option to (1) the
> flushers and (2) the list placers.
>
> The following example shows this:
>
> \definelist[testlist][criterium=all]
>
> \starttext
>
>     Regular list entries are bound to a specific location in order to
>     get the right pagenumber etc.\ associated. When pushing something
>     inbetween (in mkiv) it ends up directtly in the list. This is the
>     default because otherwise users will wonder why spacing might get
>     messed up (due to an unseen but present node). It is possible to
>     force a location by explicitly setting \type {location} to \type
>     {here}.
>
>     Another way to force a certain order is to set the \type {order}
>     variable when placing a list. The \type {command} option only
>     pushes commands into the right order, and \type {all} orders all
>     entries (which might be too much). In this case no specific
>     location is needed with the inbetween method. Maybe additional
>     mechanisms show up some day.
>
>     \subject{normal}  \placelist[testlist]
>     \subject{command} \placelist[testlist][order=command]
>     \subject{all}     \placelist[testlist][order=all]
>
>     \page \input tufte
>
>     \writetolist     [testlist]               {1} {One}
>     \writebetweenlist[testlist] {\blackrule[color=red,width=\hsize]}
>
> \writebetweenlist[testlist][location=here]{\blackrule[color=blue,width=\hsize]}
>     \writetolist     [testlist]               {2} {Second}
>     \writetolist     [testlist][location=none]{W} {Whatever}
>     \writebetweenlist[testlist] {\blackrule[color=green,width=\hsize]}
>
> \stoptext
>
> I admit that it's not an easy mechanism but any default would at some
> point trigger complaints. So it probably needs to be wikified.
>
> Hans
>

Thanks for this. It's been wikified in the reference wiki:
http://wiki.contextgarden.net/Reference/en/writebetweenlist

Bests 

-- 
Marco

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