How do I test for empty labeltext?

How do I test for empty labeltext?

[Mojca Miklavec]

Hello,

The following code

\setuplabeltext[test=]
test is \doifemptyelse{\labeltext{test}}{empty}{not empty}

doesn't work as intended for the reasons that I approximately
understand (not exactly, but I understand that there might be a lot of
weird stuff returned when I ask for labeltext). However I have no idea
how to check if text is empty or not.

As an exception :) :) :), MKIV hints should be highly appreciated and
enough for this particular application.

Mojca


PS: the extended example looks approximately as follows:

\def\document#1#2{
    \setuplabeltext[name={{#1}},company={{#2}}]
    \startstandardmakeup
    \setups{content}
    \setups{decoration}
    \stopstandardmakeup
}

\startsetups content
    This is for \labeltext{name}%
    \doifemptyelse{\labeltext{company}}{.}{, working for \labeltext{company}.}
\stopsetups

I have no problem changing the complete code and I can already find a
workaround by defining some new "if" inside definition of \document,
but I'm still slightly curious to know how to test for existence of a
label. The sources contain
    definelabels("setuplabeltext", data.texts, true)
and it is not too clear to me how to decrypt the rest with too much pain.
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Re: How do I test for empty labeltext?

[Hans Hagen]

On 24-10-2011 19:41, Mojca Miklavec wrote:
> Hello,
>
> The following code
>
> \setuplabeltext[test=]
> test is \doifemptyelse{\labeltext{test}}{empty}{not empty}
>
> doesn't work as intended for the reasons that I approximately
> understand (not exactly, but I understand that there might be a lot of
> weird stuff returned when I ask for labeltext). However I have no idea
> how to check if text is empty or not.
>
> As an exception :) :) :), MKIV hints should be highly appreciated and
> enough for this particular application.

an empty test is always somewhat special as there can be an unexpandable 
macro inside that eventually expands to nothing

you can try \doiftextelse instead

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
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___________________________________________________________________________________

Re: How do I test for empty labeltext?

[Mojca Miklavec]

On Mon, Oct 24, 2011 at 20:41, Hans Hagen <pragma@wxs.nl> wrote:
> On 24-10-2011 19:41, Mojca Miklavec wrote:
>>
>> Hello,
>>
>> The following code
>>
>> \setuplabeltext[test=]
>> test is \doifemptyelse{\labeltext{test}}{empty}{not empty}
>>
>> doesn't work as intended for the reasons that I approximately
>> understand (not exactly, but I understand that there might be a lot of
>> weird stuff returned when I ask for labeltext). However I have no idea
>> how to check if text is empty or not.
>>
>> As an exception :) :) :), MKIV hints should be highly appreciated and
>> enough for this particular application.
>
> an empty test is always somewhat special as there can be an unexpandable
> macro inside that eventually expands to nothing
>
> you can try \doiftextelse instead

Thank you very much. This works fine.

This should probably be added to
   http://wiki.contextgarden.net/System_Macros/Branches_and_Decisions
at least (possibly to reference next to labels as well), but I'm not
sure how to describe it.

Mojca
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___________________________________________________________________________________

Re: How do I test for empty labeltext?

[Hans Hagen]

On 25-10-2011 11:26, Mojca Miklavec wrote:
> On Mon, Oct 24, 2011 at 20:41, Hans Hagen<pragma@wxs.nl>  wrote:
>> On 24-10-2011 19:41, Mojca Miklavec wrote:
>>>
>>> Hello,
>>>
>>> The following code
>>>
>>> \setuplabeltext[test=]
>>> test is \doifemptyelse{\labeltext{test}}{empty}{not empty}
>>>
>>> doesn't work as intended for the reasons that I approximately
>>> understand (not exactly, but I understand that there might be a lot of
>>> weird stuff returned when I ask for labeltext). However I have no idea
>>> how to check if text is empty or not.
>>>
>>> As an exception :) :) :), MKIV hints should be highly appreciated and
>>> enough for this particular application.
>>
>> an empty test is always somewhat special as there can be an unexpandable
>> macro inside that eventually expands to nothing
>>
>> you can try \doiftextelse instead
>
> Thank you very much. This works fine.
>
> This should probably be added to
>     http://wiki.contextgarden.net/System_Macros/Branches_and_Decisions
> at least (possibly to reference next to labels as well), but I'm not
> sure how to describe it.

"If you want to know if some macro provides some typeset content you can 
use the following helper macro:" ...



-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: How do I test for empty labeltext?

[Aditya Mahajan]

On Tue, 25 Oct 2011, Mojca Miklavec wrote:

>> you can try \doiftextelse instead
>
> Thank you very much. This works fine.
>
> This should probably be added to
>   http://wiki.contextgarden.net/System_Macros/Branches_and_Decisions
> at least (possibly to reference next to labels as well), but I'm not
> sure how to describe it.

IIRC, there is some explanation in the source file (supp-box or pack-box, 
not sure which one).

Aditya
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