recursion in a table

recursion in a table

[Henning Hraban Ramm via ntg-context]

Hi,
I was playing with the example from 
https://wiki.contextgarden.net/Scaling_Rotating_Mirroring_Clipping#Location_parameter 
and tried to put it in a tabulate:


\useMPlibrary[dum]
\setupexternalfigures[width=3em,height=2em,frame=on,]

%\def\TXT{\ruledhbox{\bf(XyX)}}
\def\TXT{\externalfigure[pic]}

\starttabulate[|l|l|l|l|l|l|]
     \NC\NC normal\NC depth\NC fit\NC broad\NC high\NC\NR
     \HL
\dostepwiserecurse{0}{359}{45}{%
%\expanded{\setuprotate[rotation=\recurselevel]}
     \NC{\expanded{\recurselevel}˚}%
 
\NC{\ruledhbox{X\rotate[location=normal,rotation=\recurselevel]{\TXT}X}}%
     \NC{\ruledhbox{X\rotate[location=depth,rotation=\recurselevel] 
{\TXT}X}}%
     \NC{\ruledhbox{X\rotate[location=fit,rotation=\recurselevel] 
{\TXT}X}}%
     \NC{\ruledhbox{X\rotate[location=broad,rotation=\recurselevel] 
{\TXT}X}}%
     \NC{\ruledhbox{X\rotate[location=high,rotation=\recurselevel] 
{\TXT}X}}%
   \NC\NR}
%    \HL % error
\stoptabulate


This works, but \recurselevel is always 0. I know I must expand it (like 
in the original example), but I can’t make it work within the tabulation.
In the first column, \expanded{\recurselevel} stays 0, and 
rotation=\expanded{\recurselevel} gives an error, while the \setuprotate 
line has no effect (if I remove "rotation=\recurselevel", of course).

How would that work?

Also, \HL doesn’t work at the end, and the second line of the error 
message makes no sense:
"""
I expect to see \noalign only after the \cr of an alignment.
Proceed, and I'll ignore this case.
mtx-context     | fatal error: return code: 1
"""

Hraban
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Re: recursion in a table

[Aditya Mahajan via ntg-context]

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On Sun, 1 May 2022, Henning Hraban Ramm via ntg-context wrote:

> Hi,
> I was playing with the example from 
> https://wiki.contextgarden.net/Scaling_Rotating_Mirroring_Clipping#Location_parameter 
> and tried to put it in a tabulate:
> 
> 
> \useMPlibrary[dum]
> \setupexternalfigures[width=3em,height=2em,frame=on,]
> 
> %\def\TXT{\ruledhbox{\bf(XyX)}}
> \def\TXT{\externalfigure[pic]}
> 
> \starttabulate[|l|l|l|l|l|l|]
>      \NC\NC normal\NC depth\NC fit\NC broad\NC high\NC\NR
>      \HL
> \dostepwiserecurse{0}{359}{45}{%
> %\expanded{\setuprotate[rotation=\recurselevel]}
>      \NC{\expanded{\recurselevel}˚}%

Untested, but I think that you might need:

\expanded{\NC \recurselevel \noexpand\NC ... }

> This works, but \recurselevel is always 0. I know I must expand it (like 
> in the original example), but I can’t make it work within the tabulation.
> In the first column, \expanded{\recurselevel} stays 0, and 
> rotation=\expanded{\recurselevel} gives an error, while the \setuprotate 
> line has no effect (if I remove "rotation=\recurselevel", of course).
> 
> How would that work?

Remind me of a more-than-a-decade-old discussion on the mailing list, summarized here:

https://adityam.github.io/context-blog/post/tex-programming/

> Also, \HL doesn’t work at the end, and the second line of the error 
> message makes no sense:

I find that in such cases, using Lua (CLD) is the simplest solution

Aditya

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Re: recursion in a table

[Hans Hagen via ntg-context]

On 5/2/2022 2:30 AM, Aditya Mahajan via ntg-context wrote:

> \expanded{\NC \recurselevel \noexpand\NC ... }

There is no need for \noexpand before \NC. Even \NR is protected. In 
MKIV there are some more sensitive ones like \FR but in LMTX these are 
defined as \noaligned which permits them being protected too (the 
engine's alignments scanners have some lookahead properties that cna 
otherwise interfere).

\starttabulate[||]
     \NC \infofont\meaningasis \NC \NC \NR
     \NC \infofont\meaningasis \NR \NC \NR
     \NC \infofont\meaningasis \HL \NC \NR
     \NC \infofont\meaningasis \FL \NC \NR
\stoptabulate

> Remind me of a more-than-a-decade-old discussion on the mailing list, summarized here:
> 
> https://adityam.github.io/context-blog/post/tex-programming/
> 
>> Also, \HL doesn’t work at the end, and the second line of the error
>> message makes no sense:

As you're not afraid of low level code:

\starttext

\starttabulate[|r|c|]
     \NC $T$ \NC what \NC \NR
     \HL
     \expandedloop 0 359 45 {
         \NC \number\currentloopiterator ˚ \NC \NC \NR
     }
\stoptabulate

\stoptext

So, you can play with:

\expandedloop
\unexpandedloop
\localcontrolledloop
\quitloop
\currentloopiterator
\currentloopnesting
\lastloopiterator

if you want a challenge for a new blog post.

Hans

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