Optional argument to \item to appear in brackets after the counter

Question

Usually, when you have the following document:

\documentclass{article}
\usepackage{enumitem}
\begin{document}
\begin{enumerate}
\item Mary
\item[had] a little 
\item lamb
\end{enumerate}
\end{document}

It will format as

  1. Mary
had a little
  2. lamb

I would want it to format as

  1. Mary
  2 (had). a little
  3. lamb

In other words, I would like the optional argument that can be passed to an \item not to replace the usual label, but I want it to appear additionally. In particular, the counter should still be stepped.

This might seem like a subtlety, but note that the argument should appear before the period and after the counter. In fact, this is just a minimal example - I would like to have greater flexibility in placing the optional argument within the label.

Is there a way to do this with the enumitem package?

A simple solution would be \item (had) a little, but perhaps that is not an option. — Peter Grill, Mar 08 '13 at 08:09
What about references? How should item 2 be referenced? With 2 or with 2(had)? — egreg, Mar 08 '13 at 08:34
It would be interesting to know why you don't just do it as Peter Grill suggests. Could you please add that to the question? Thanks! — Hendrik Vogt, Mar 08 '13 at 13:37
It's basically in the comment to Peters answer, but I put it in the original question as well. — Jesko Hüttenhain, Mar 09 '13 at 00:10

score 4 · Accepted Answer · answered Mar 08 '13 at 08:57

4

You could try it this way:

\documentclass{article}
\usepackage{enumitem}
\newcommand\labeltext{}
\newcommand\specialitem[1][]{%
 {\renewcommand\labeltext{ (#1)}\item\leavevmode}}
\begin{document}
\begin{enumerate}[label=\arabic*\noexpand\labeltext.]
\item Mary
\specialitem[had] a little 
\item lamb
\end{enumerate}
\end{document}

Remarks:

I'm using a special command but it should also be possible to patch \item but then you would loose the standard behaviour.
The correct alignment of the label is left as an exercise ;-).

answered Mar 08 '13 at 08:57

Ulrike Fischer

327,261

That's clever! Also, it does exactly what I want. Also, exercise solved. Thanks a bunch! =) – Jesko Hüttenhain Mar 09 '13 at 00:08
I do not fully understand, what you do, so it might be superfluous, but: Jesko writes in a comment to egreg above, that for the references he wants only the counters without the added text. In enumitem for such cases exists an option ref, here I would suggest ref=\arabic*.. – Speravir Mar 09 '13 at 03:51
No no, don't worry, this is precisely what I wanted. I am using cleveref anyway. – Jesko Hüttenhain Mar 09 '13 at 15:25

score 3 · Answer 2 · edited Jun 10 '20 at 12:32

You can define you own custom environment in which you redefine \item macro:

enter image description here

Notes:

If you wish to redefine a macro that has optional parameters, you have to use \LetLtxMacro from the letltxmacro package . A detailed description of \LetLtxMacro can be found at this question at When to use \LetLtxMacro?.
I have used the xstring package for string comparison as I prefer its syntax, but this can be done without that pacakge if required.

Code:

\documentclass{article}
\usepackage{enumitem}
\usepackage{xstring}
\usepackage{letltxmacro}
\LetLtxMacro{\OldItem}{\item}
\newenvironment{MyEnumerate}[1][]{%
    \renewcommand{\item}[1][]{\OldItem \IfStrEq{##1}{}{}{(##1)}}%
    \begin{enumerate}[#1]%
}{%
    \end{enumerate}%
}%
\begin{document}
\begin{MyEnumerate}
    \item Mary
    \item[had] a little 
    \item lamb
\end{MyEnumerate}
\end{document}

This might seem like a subtlety, but I would want the argument to appear before the period and after the counter. More precisely, I would like to have greater flexibility in placing the optional argument within the label. — Jesko Hüttenhain, Mar 08 '13 at 08:23

Optional argument to \item to appear in brackets after the counter

2 Answers2

Notes:

Code:

Linked