Conditionals and arrayjobx

Question

I am struggling with the use of conditionals, I have a basic example given below that will output the table included.

The code starts by defining \myletterA as the A character, and an array called \test as A,B,C. I have a function called \indenterer that I call inside my table loop below.

\documentclass[12pt]{article}
\usepackage[a6paper,landscape]{geometry}

\usepackage{arrayjobx}
\usepackage{ifthen}

\def\tand{&}

\begin{document}

\newcommand{\myletterA}{}
\newcommand{\myletterwriter}[1]{\renewcommand\myletterA{#1}}
    \myletterwriter{A}

\newarray\test
\newcommand{\indenterer}{%
    \readarray{test}{A&B&C}%writes A,B,C to array test
    \checktest(1)%reads the first value
    \cachedata%returns the value last read by \checktest
    \myletterA%returns the value stored i.e. A
    \ifx\cachedata\myletterA%
    a% \true case
    \else%
    b% false case
    \fi%
}

\newcounter{it}
\begin{tabular}{ll}%
\hline%
  \setcounter{it}{1}%
  \whiledo{\theit<4}{%
    {\indenterer} Y \tand z \\%
  \stepcounter{it}%
  }%
\end{tabular}

space
    \checktest(1)
    \cachedata
    \myletterA

\end{document}

The output lines of the table should display \cachedata\myletterA_ Y Z where the _ is either an a or b. So my question is why is this code always executing the false case (note the letter b instead of a) even though both \cashdata and \myletterA expand to give the same result?

Answer 1

It's easy. ;-) With

\newcommand{\myletterwriter}[1]{\renewcommand\myletterA{#1}}

the macro \myletterA is \long, whereas \cachedata is defined with \def that makes it non \long.

Just do

\newcommand{\myletterwriter}[1]{\renewcommand*\myletterA{#1}}