How can I add lines numbers (with Lineno) in the Abstract environment as defined in an Overleaf template

Question

Problem:

How can I add lines numbers (with lineno) in the Abstract environment as defined in this Overleaf template?

The following piece of code is the Abstract definition, which is included in the wlscirep.cls file:

\def\xabstract{abstract}
\long\def\abstract#1\end#2{\def\two{#2}\ifx\two\xabstract 
\long\gdef\theabstract{\ignorespaces#1}
\def\go{\end{abstract}}\else
\typeout{^^J^^J PLEASE DO NOT USE ANY \string\begin\space \string\end^^J
COMMANDS WITHIN ABSTRACT^^J^^J}#1\end{#2}
\gdef\theabstract{\vskip12pt BADLY FORMED ABSTRACT: PLEASE DO
NOT USE {\tt\string\begin...\string\end} COMMANDS WITHIN
THE ABSTRACT\vskip12pt}\let\go\relax\fi
\go}

My attempt:

In the main.tex file I added the following code:

\documentclass[fleqn,10pt]{wlscirep}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[displaymath]{lineno}
\linenumbers

\makeatletter
\let\LN@abstract\abstract
\let\LN@endabstract\endabstract
\renewcommand{\abstract}{\linenomath\LN@abstract}
\renewcommand{\endabstract}{\LN@endabstract\endlinenomath}
\makeatother



\begin{abstract}
bla bla bla bla bla bla bla bla bla bla ....
bla bla bla bla bla bla bla bla bla bla ....
bla bla bla bla bla bla bla bla bla bla ....
bla bla bla bla bla bla bla bla bla bla ....
\end{abstract}




\begin{document}

\flushbottom
\maketitle
\thispagestyle{empty}


\section*{My first section}
Here I write about .....


\end{document}

but I do not get the lines numbers in the Abstract. Any idea?

Answer 1

I cannot really recommend using this document class, since it defines certain things in a way that does not really allow easy amendments. Especially the defintion of the abstract environment is a bit peculiar.

I would suggest to redefine the abstract environment using a \parbox which would then also allow the use of line numbers:

\documentclass[fleqn,10pt]{wlscirep}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lineno}

\usepackage{lipsum}

\RenewDocumentEnvironment{abstract}{+b}{%
    \gdef\theabstract{\parbox{\linewidth}{\internallinenumbers #1}}%
}{}

\title{Foo}
\author{Bar Baz}

\begin{abstract}
\lipsum[1]
\end{abstract}

\begin{document}

\flushbottom
\maketitle

\section*{My first section}
Here I write about ...

\end{document}

This has, however, an unwanted side-effect, namely if you add line numbers to the complete document as well, the abstract box will get another additional line number because it is inside a parbox (actually inside two nested parboxes).

---

On second thought, it is probably a better idea to patch \@maketitle directly:

\documentclass[fleqn,10pt]{wlscirep}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lineno}
\linenumbers

\usepackage{lipsum}

\makeatletter
\patchcmd\@maketitle{%
        {%
        \noindent
        \colorbox{color2}{%
            \parbox{\dimexpr\linewidth-2\fboxsep\relax}{%
            \sffamily\small\textbf\\\theabstract
            }%
        }%
        }%
    }{%
        \nolinenumbers{%
        \noindent
        \colorbox{color2}{%
            \parbox{\dimexpr\linewidth-2\fboxsep\relax}{%
            \internallinenumbers \sffamily\small\theabstract
            }%
        }%
        }%
    }
    {\wlog{true}}{\wlog{false}}
\makeatother

\title{Foo}
\author{Bar Baz}

\begin{abstract}
\lipsum[1]
\end{abstract}

\begin{document}

\flushbottom
\maketitle

\section*{My first section}
Here I write about ...

\end{document}