3

In the following code, I write two macros for \begin{enumerate}...\end{enumerate}. In trying to get more than one optional argument, I used the method in More than one optional argument for newcommand. However, when I add an extra linebreak between \items, the \NewDocumentCommand macro fails while the original \begin{enumerate}...\end{enumerate} is fine, and \newcommand macro is also fine.

\documentclass{article}
\usepackage{amsmath}
\usepackage{xparse}

% if do enumitem before enumerate, cause error????? https://tex.stackexchange.com/questions/238691/enumitem-always-throwing-errors
\usepackage{enumerate}
\usepackage[shortlabels]{enumitem}


\newcommand{\myenumerate}[2][4]{\begin{enumerate}[(a), leftmargin=0.2in,parsep=0pt,itemsep=#1pt]
#2
\end{enumerate}}


\NewDocumentCommand{\myenumeratebad}{ O{10} O{a} m }{\begin{enumerate}[(#2),leftmargin=0.3in,parsep=0pt,itemsep=#1pt,topsep=8pt]
#3
\end{enumerate}}


\begin{document}


\begin{enumerate}[(i),leftmargin=0.3in,parsep=0pt,itemsep=4pt,topsep=8pt]
\item awef


\item awef
\end{enumerate}


\myenumerate[10]{
\item awe


\item awf
}


\myenumeratebad[10][i]{
\item awe
\item awf
}


\myenumeratebad[10][i]{
\item awe
\item awf
}


\end{document}

P.S. in making my MWE, there was an issue putting enumitem before enumerate, but not the other way around. I only learned about this from a comment here Enumitem always throwing errors.

Qrrbrbirlbel
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D.R
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    you can not use enumerate and enumiten at the same time you are using enumitem here so delete the enumerate package – David Carlisle Oct 05 '22 at 06:58
  • @DavidCarlisle I think if I delete the enumerate package I lose the ability to write [(a)] or [(i)] to specify what type of bullet points I want – D.R Oct 05 '22 at 15:53
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    No you do not: you are not using enumerate at all. If you have two packages one does \def\qqq{a} the other does \def\qqq{b} then you can not load both packages and have \qqq magically be a and b at the same time. You load enumitem second so it wins and loading enumerate first just makes things slower. – David Carlisle Oct 05 '22 at 15:58
  • @DavidCarlisle ok I see, thank you for the clarification. – D.R Oct 05 '22 at 18:29

1 Answers1

4

By default \newcommand creates a macro that is defined long, i.e. accepting paragraph parameters, i.e. an empty line. (A short macro uses \newcommand*.)

With \NewDocumentCommand all paramaters are by default short – unless the argment is prefixed by a +. (Yes, you can specify the length on an “argument-by-argument basis”, page 3 of the xparse manual.)

So, you're going to need

\NewDocumentCommand{\myenumeratebad}{ O{10} O{a} +m }{%
  \begin{enumerate}[(#2),leftmargin=0.3in,parsep=0pt,itemsep=#1pt,topsep=8pt]
  #3
  \end{enumerate}}

Though, you might just define your own environment again:

\NewDocumentEnvironment{myenumerateenv}{O{10} O{a}}{%
  \begin{enumerate}[(#2),leftmargin=0.3in,parsep=0pt,itemsep=#1pt,topsep=8pt]}
  {\end{enumerate}}

which you can use with or without empty lines.

\begin{myenumerateenv}[10][i]
\item awe

\item awf
\end{myenumerateenv}
Qrrbrbirlbel
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