[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]
           \bTABLEhead
             \bTR[nc=2]
               \bTH Direct\eTH
             \eTR
           \eTABLEhead
           \bTABLEbody
               \processcommacommand[\Sets]\doTableRow
           \eTABLEbody
         \eTABLE

         \processcommacommand[\Sets]\doInlineTextExpA

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

         \processcommacommand[\Sets]\doInlineTextExpB

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

    \stoptext



-- 
RIk

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