# [NTG-context] Expansion help needed, getvariable and TABLE

Rik Kabel context at rik.users.panix.com
Wed Jan 31 15:47:11 CET 2018

On 2018-01-31 01:04, Wolfgang Schuster wrote:
>
>> Rik Kabel <mailto:context at rik.users.panix.com>
>> 31. Januar 2018 um 03:10
>>
>> Listers,
>>
>> I have a problem, and a question on ConTeXt programming efficiency.
>>
>> In the example below, I have a set of variables. When these are
>> reference directly via \getvariable, everything works as expected in
>> simple text and in TABLEs. When I \define a macro to the
>> \getvariable, that works in simple text, but only the value of the
>> last iteration appears in the TABLE. The macro definition is saved
>> and when it is used, that is the value that it has.
>>
>> So, how can I \define (or \def, ...) a macro to the expanded value to
>> avoid this? That is the problem.
>>
>> The question is, Is there is any advantage to be had in doing this?
>> Assume that the value is referenced many (tens of) times. There seems
>> to be an aesthetic value of factoring out the multiple identical
>> instances of the \getvariable syntax and assigning a more
>> semantically informative name, but beyond that, is there any other value?
>>
>>
> Natural tables collect the content of all cells to perform the width
> and height calculations
> and you have to expand the content of the cells to get the current
> value of \getvariable.
>
> \starttexdefinition unexpanded doTableRow #SET
>     \bTR
>       \expanded{\bTC\getvariable{#SET}{a}\eTC}
>       \expanded{\bTC\getvariable{#SET}{b}\eTC}
>     \eTR
> \stoptexdefinition
>
>
> BTW: You can use the \processcommacommand command when you save your
> lists in a macro (no need for \expandafter).
>
> \defineexpandable\Sets{one,two}
>
> \processcommacommand[\Sets]\doInlineTextExp
>
>
> Wolfgang

Thank you for the help and the processcommacommand bit. However, the
problem is still there (and I was just wrong in my own follow-up).

Below is an updated example with and without the \expanded{\bTC...

It does not seem to make a difference here, but perhaps it is needed in
some situations.

My question is about factoring the \getvariable out of the \bTC rows (in
this example) and \defining a simpler macro to hold the value. Should it
be done, and if so, how?

% macros=mkvi engine=luajittex

\setvariables      [one]
[a=1aaaaaaaa,b=1b,c=1c]
\setvariables      [two]
[a=2a,b=2bbbbbbbbbbbbbbbb,c=2c]

\defineexpandable  \Sets
{one,two}

\starttexdefinition unexpanded doInlineText #SET
Direct: \getvariable{#SET}{a} \getvariable{#SET}{b}\
\getvariable{#SET}{c}\par
\stoptexdefinition

\starttexdefinition unexpanded doTableRow #SET
\bTR
\bTC\getvariable{#SET}{a}\eTC
\bTC\getvariable{#SET}{b}\eTC
\bTC\getvariable{#SET}{c}\eTC
\eTR
\stoptexdefinition

\starttexdefinition doInlineTextExpA #SET
\define\A{\getvariable{#SET}{a}}
\define\B{\getvariable{#SET}{b}}
\define\C{\getvariable{#SET}{c}}
Factored A: \A\ \B\ \C\par
\stoptexdefinition

\starttexdefinition doTableRowExpA #SET
\define\A{\getvariable{#SET}{a}}
\define\B{\getvariable{#SET}{b}}
\define\C{\getvariable{#SET}{c}}
\bTR
\bTC\A\eTC
\bTC\B\eTC
\bTC\C\eTC
\eTR
\stoptexdefinition

\starttexdefinition doInlineTextExpB #SET
\define\A{\getvariable{#SET}{a}}
\define\B{\getvariable{#SET}{b}}
\define\C{\getvariable{#SET}{c}}
Factored B: \A\ \B\ \C\par
\stoptexdefinition

\starttexdefinition doTableRowExpB #SET
\define\A{\getvariable{#SET}{a}}
\define\B{\getvariable{#SET}{b}}
\define\C{\getvariable{#SET}{c}}
\bTR
\expanded{\bTC\A\eTC}
\expanded{\bTC\B\eTC}
\expanded{\bTC\C\eTC}
\eTR
\stoptexdefinition

\starttext

\processcommacommand[\Sets]\doInlineText

\bTABLE[frame=off]
\bTR[nc=2]
\bTH Direct\eTH
\eTR
\bTABLEbody
\processcommacommand[\Sets]\doTableRow
\eTABLEbody
\eTABLE

\processcommacommand[\Sets]\doInlineTextExpA

\bTABLE[frame=off]
\bTR[nc=2]
\bTH Factored A\eTH
\eTR
\bTABLEbody
\processcommacommand[\Sets]\doTableRowExpA
\eTABLEbody
\eTABLE

\processcommacommand[\Sets]\doInlineTextExpB

\bTABLE[frame=off]
\bTR[nc=2]
\bTH Factored B\eTH
\eTR
\bTABLEbody
\processcommacommand[\Sets]\doTableRowExpB
\eTABLEbody
\eTABLE

\stoptext

--
RIk

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ntg.nl/pipermail/ntg-context/attachments/20180131/72473731/attachment-0001.html>