# Nesting of case-selecting functions [closed]

Can case-selecting functions like \prg_case_int or \prg_case_str be nested? If so I will provide some examples of very weird results I observe with nesting.

REVISION:

I messed up the syntax suggested in the interface3 document by omitting some of the <code case> strings. The revised code of my experiment now works and looks like this:

%document name: LaTeX3_interface3.tex
%RN 15/3/2012
%   OBJECTIVE: Nesting case-selecting functions prg_case_str or prg_case_int.
%   REFERENCE: The LaTeX3 Intefaces, 8 Feb 2012 (interface3.pdf), page 38ff.
%   (1) on the first attempt failed to define all of the <code case> strings and the whole
%   thing turned pear shaped
%   (2) the printed messages in the result are not properly formatted but that's due
%   to my inexperience in LaTeX2 and needs to be addressed seperately.
%=====================================================================================

\documentclass{article}
%\usepackage{expl3}
\usepackage{amsmath,xparse}
\ExplSyntaxOn
\NewDocumentCommand{\myCommand}{ m m m }
{
\prg_case_str:nnn { #1 }
{
{1a}
{
\prg_case_str:nnn { #2 }
{
{2A} %{case 1a:2A\\}
{
\prg_case_str:nnn { #3 }
{
{3\alpha}   {case 1a:2A:3\alpha\\}
{3\beta}    {case 1a:2A:3\beta\\}
{3\gamma}   {case 1a:2A:3\gamma\\}
}
{None of 1a:2A: 3\alpha, 3\beta, 3\gamma \\}
}
{2B} %{case 1a:2B\\}
{
\prg_case_str:nnn { #3 }
{
{3\alpha}   {case 1a:2B:3\alpha\\}
{3\beta}    {case 1a:2B:3\beta\\}
{3\gamma}   {case 1a:2B:3\gamma\\}
}
{None of 1a:2B: 3\alpha, 3\beta, or 3\gamma\\}
}
{2C} %{case 1a:2C\\}
{
\prg_case_str:nnn { #3 }
{
{3\alpha}   {case 1a:2C:3\alpha\\}
{3\beta}    {case 1a:2C:3\beta\\}
{3\gamma}   {case 1a:2C:3\gamma\\}
}
{None of 1a:2C: 3\alpha, 3\beta, 3\gamma\\}
}
}
{None of 1a: 2A, 2B, 2C\\}
}
{1b}
{
\prg_case_str:nnn { #2 }
{
{2A}    {case 1b:2A\\}
{2B}    {case 1b:2B\\}
{2C}    {case 1b:2C\\}
}
{None of 1b: 2A, 2B, 2C\\}
}
{1c}
{
\prg_case_str:nnn { #2 }
{
{2A}    {case 1c:2A\\}
{2B}    {case 1c:2B\\}
{2C}    {case 1c:2C\\}
}
{None of 1c: 2A, 2B, 2C\\}
}
}
{None of 1a, 1b, 1c\\}
}
%etc. etc.
\ExplSyntaxOff

\begin{document}

$\myCommand{1a}{2A}{3\alpha}$
$\myCommand{1a}{2B}{3\beta}$
$\myCommand{1a}{2C}{3\gamma}$
$\myCommand{1b}{2A}{3gamma}$
$\myCommand{1b}{2B}{3gamma}$
$\myCommand{1b}{2C}{3gamma}$
$\myCommand{x}{2A}{3gamma}$
$\myCommand{1a}{y}{3gamma}$
$\myCommand{1a}{2C}{3gamma}$
$\myCommand{1b}{2A}{3gamma}$
$\myCommand{z}{2B}{3gamma}$
$\myCommand{1b}{2C}{3gamma}$

\end{document}


If I knew how to import the resulting .pdf document I would.

My apologies for starting a wild goose chase. My only excuse is that the LaTeX syntax is quite tricky to get right in the absence of automated editing facilities that would as a minimum generate correct indentations. Perhaps such LaTeX3 editing facilities are already available, if they are I would love to hear about them.

-

## closed as too localized by Werner, egreg, Andrey Vihrov, Joseph Wright♦Mar 16 '12 at 8:51

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Of course they can. What are these examples? – egreg Mar 15 '12 at 15:37
yes please provide them, as always there my be bugs but I'm not aware any offcial restrictions – Frank Mittelbach Mar 15 '12 at 16:06
Obviously I am doing something very stupid with my syntax here. I'll try to fix it before I ask for more help. Thanks. – Reinhard Neuwirth Mar 15 '12 at 21:33
OK, I made it work. I had left out some of the <code case> strings. Would like to send you my code example but it is too big to fit into this COMMENT. Should I make this a new question or what other options do I have to send my code? – Reinhard Neuwirth Mar 15 '12 at 23:18
@ReinhardNeuwirth: It seems like you've solved your original problem. As such, I'm voting to close this question. – Werner Mar 16 '12 at 7:05