if statement problem

Question

I am having a problem with some code and I could use some help. I have been using this implementation for a long time now and no problems before.

Here is how I store all my variables

\newcommand{\@srulesI}{}
\newcommand{\@srulesII}{}
\newcommand{\srules}[2]{
    \renewcommand\@srulesI{#1}
    \renewcommand\@srulesII{#2}}%%%%%

Here is the logic for it.

\if\@srulesII\@emptymacro
\else
    \begin{minipage}{\linewidth}
        \raggedright
        {\bfseries \rule{0em}{1.5em}\@srulesI}

        \@srulesII
    \end{minipage}
\fi

These pieces of code work

\srules{}{}%%%%%
\srules{}{asdf}%%%%%
\srules{asdf}{}%%%%%
\srules{asdf}{asdf}%%%%%
\srules{asdf}{asdf\rule{0.5in}{0.5in}}%%%%%

This piece of code doesnt work, which is coincidentally the one I need.

\srules{asdf}{\rule{0.5in}{0.5in}}%%%%%

It gives an error of "Incomplete \if; all text was ignored after line 40. "

Does anyone know why? I dont know why the \rule makes the compiler have a fit.

Second question. Is what I am doing really the best way to declare and store variables? Cause I have like 50 variables and my .cls file is getting huge.

Answer 1

For macro-comparison, use \ifx, not \if:

\documentclass{article}

\makeatletter
\newcommand{\@srulesI}{}
\newcommand{\@srulesII}{}
\newcommand{\srules}[2]{
  \renewcommand\@srulesI{#1}
  \renewcommand\@srulesII{#2}}%%%%%
\newcommand{\@emptymacro}{}
\makeatother

\begin{document}

\srules{asdf}{\rule{0.5in}{0.5in}}%%%%%
\makeatletter
\ifx\@srulesII\@emptymacro
\else
  \begin{minipage}{\linewidth}
    \raggedright
    {\bfseries \rule{0em}{1.5em}\@srulesI}

    \@srulesII
  \end{minipage}
\fi
\makeatother

\end{document}

---

In answer to your second question, it really depends on your user interface. Note that arguments to macros are limited to 9, although that can be increased. A key-value interface in such instances are typically preferred.