Shorthand for variables lead to name clash

Question

In formulas I need often the same constants and variables with lot of "make-up".

I want to have readable and maintainable LaTeX code, so I thought about writing \newcommands like

\newcommand*{\Cref}{C_{\textrm{ref}}} %very short example
..
\[ \Cref \cdot U = Q \]

But \Cref is already in use by \usepackage{cleveref} and so on …

Finally I run quickly out of short, nice commands.

I am looking for someone who has had the same problem and had a brilliant idea.

Answer 1

Defining \Cref so that it does different things in different contexts (for instance if it has an empty argument or not, or if it is in math or text mode) is definitely not recommendable, as it is confusing.

You can define a "shortcut" producing command:

\makeatletter
\newcommand{\scut}[1]{\@nameuse{myscut@#1}}
\newcommand{\defineshortcut}[2]{\global\@namedef{myscut@#1}{#2}}
\makeatother

Then you can set in your preamble

\defineshortcut{Cref}{C_{\textnormal{ref}}}

and use \scut{Cref} in your document. You can even say

\defineshortcut{C_ref}{C_{\textnormal{ref}}}

and use \scut{C_ref}, if you prefer.

If \scut is perceived as too long, one can use a shorter sequence; \s is free, while \S prints § (so it could be redefined, though with care, because some document could use the original command).

---

One can use a "one character shortcut", for instance | or " (if babel is not used); the following definitions allow also for "parameterized" shortcuts with the same syntax as \newcommand.

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\newcommand{\scut}[1]{\@nameuse{myscut@shortcut@#1}}
\newcommand{\defineshortcut}[1]{\expandafter\newcommand\csname myscut@shortcut@#1\endcsname}
\newcommand{\useshortcutsymbol}[1]{%
  \global\expandafter\chardef\csname myscut@catcode@#1\endcsname\catcode`#1\relax
  \catcode`#1=\active
  \begingroup\lccode`~=`#1\relax
  \lowercase{\endgroup\def~##1~}{\@nameuse{myscut@shortcut@##1}}}
\newcommand{\undefineshortcutsymbol}[1]{%
  \catcode`#1\csname myscut@catcode@\string#1\endcsname}
\makeatother

\defineshortcut{C}[1]{C_\textnormal{#1}}
\defineshortcut{Cref}{C_\textnormal{ref}}

\begin{document}
\useshortcutsymbol{|}

$\scut{C}{ref}\quad\scut{Cref}$

$|C|{ref}\quad|Cref|$

\undefineshortcutsymbol{|}

$|C|$

\end{document}

However I wouldn't use this kind of "too short" shortcuts, which are error prone. The \useshortcut command should receive a non special ASCII character as its argument; high bit set characters are definitely not safe, because they are treated differently in different encodings.

Answer 2

Here's a simple approach: make a command for the subscripted "ref".

 \newcommand*\sref{_{\textrm{ref}}}

This makes the "ref" akin to a diacritic or operator: This makes it easier to systematically refer to "ref"-variables in your text. I routinely do the same to define transposes and hermitian adjoints, as in

 \newcommand*\trans{^{\textsf{T}}}
 \newcommand*\herm{^\dagger} 

Answer 3

In other programming languages this is usually solved using namespaces. For LaTeX, there is the namespc package which provides

rudimentary C++-like namespaces in LaTeX.

Example:

\documentclass{scrartcl}
\pagestyle{empty}

\usepackage{amsmath}
\usepackage{namespc}
\usepackage{cleveref}
%
\newcommand{\overwritecommand}[1]{\let#1\undefined\newcommand{#1}}
%
\begin{document}
  \section{First section}
  \label{sec:first}

  \namespace{shortcuts}{%
    \overwritecommand{\Cref}{mycref}
  }{}

  This is the original definition: \Cref{sec:first}

  \begin{shortcuts}
    This is used from within the ``shortcuts'' environment: \Cref
  \end{shortcuts}

  \begin{align*}
    \usingnamespace{shortcuts}
    \text{Equation} = \text{\Cref}
  \end{align*}

  This is to access the macro explicitly: \::shortcuts::Cref::
\end{document}

To be honest, I have found it only through a dedicated search, I have never seen it in use before. I am going to be using it from now on for the problem you described.