Expand key-values with \def of \newcommand?

Question

I have multiple repeated

\begin{enumerate}[label=A\alph*), ref=A\alph*]

and I want to reduce code duplication. I would also like to avoid creating new environments if possible. I just want a simple way (if there is one) to do something like this:

\newcommand{\enumopts}[1]{label={#1}\alph*), ref={#1}\alph*}
\begin{enumerate}[\enumopts{A}]

The example above is not working. If it is relevant, I am referring to the enumitem package.

I should note that the following works:

\newcommand{\elabel}[1]{{#1}\alph*)}
\newcommand{\eref}[1]{{#1}\alph*}
\begin{enumerate}[label=\elabel, ref=\eref]

How can I do it?

In this specific case, setlist from enumitem package → https://tex.stackexchange.com/questions/313463/changing-the-default-numbering-scheme-in-enumerate-environment. in the general case, you need to learn some TeX programming. — user202729, Nov 29 '23 at 11:44
If enumitem was using expkv as the key=value implementation you could use its expansion notation. You could even write a wrapper using expkv to have arbitrary key lists with expansion notation, but I guess simply defining a new key for enumitem as done in the accepted answer is easier and way more straight forward... :) — Skillmon, Nov 29 '23 at 16:05

score 10 · Accepted Answer · answered Nov 29 '23 at 11:54

You can define new keys:

\documentclass{article}
\usepackage{enumitem}
\SetEnumitemKey{alph}{label=#1\alph*), ref=#1\alph*}
\begin{document}
\begin{enumerate}[alph=A]
\item abc\label{test}
\end{enumerate}
\ref{test}
\begin{enumerate}[alph=B]
\item abc
\end{enumerate}
\end{document}

score 0 · Answer 2 · answered Nov 30 '23 at 11:43

Though I strongly recommend the answer provided by @UlrikeFischer for the problem at hand, for the more general question on how to expand a macro inside of a key list the following defines such a preprocessor using expkv.

This allows to use expkv's expansion notation to specify precise expansions of single list elements.

In the following example I use these expansion rules:

o\r expand the first token once (o) and reinsert the result as key=value input (\r)
R expand the single token once (or if it's a register, expand to the register's contents), then reinsert the result as key=value input (not usable for the macro taking argument \enumopts).

\documentclass{article}
\usepackage{expkv}
\makeatletter
\newcommand\kvpreproc[2]
  {%
    \expanded
      {\unexpanded{#1}{\expanded{\ekvparse\kvpreproc@k\kvpreproc@kv{#2}}}}%
  }
\newcommand\kvpreproc@k[1]{, {\unexpanded{#1}}}
\newcommand\kvpreproc@kv[2]{, {\unexpanded{#1}}= {\unexpanded{#2}}}
\makeatother
\usepackage{enumitem}
\newcommand{\enumopts}[1]{label={#1}\alph), ref={#1}\alph}
\newcommand\moreopts{labelsep=1em}
\begin{document}
\kvpreproc{\begin{enumerate}[}{nosep, o\r: \enumopts{A}, R: \moreopts}]
  \item foo
  \item bar
  \item baz
\end{enumerate}
\kvpreproc{\begin{enumerate}[}{nosep, o\r: \enumopts{A}}]
  \item foo
  \item bar
  \item baz
\end{enumerate}
\end{document}

Expand key-values with \def of \newcommand?

2 Answers2