[Tex/LaTex] Define abstract environment in book

abstractdocument-classespreamble

I want to define an abstract environment for \documentclass{book}. Therefore, I copied the relevant definitions from report.cls from here into my preamble. But it doesn't work. Where's the problem?

\documentclass[11pt, a4paper]{book}

\usepackage{lipsum}

\makeatletter
\if@titlepage
  \newenvironment{abstract}{%
      \titlepage
      \null\vfil
      \@beginparpenalty\@lowpenalty
      \begin{center}%
        \bfseries \abstractname
        \@endparpenalty\@M
      \end{center}}%
     {\par\vfil\null\endtitlepage}
\else
  \newenvironment{abstract}{%
      \if@twocolumn
        \section*{\abstractname}%
      \else
        \small
        \begin{center}%
          {\bfseries \abstractname\vspace{-.5em}\vspace{\z@}}%
        \end{center}%
        \quotation
      \fi}
      {\if@twocolumn\else\endquotation\fi}
\fi
\makeatother

\begin{document}

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

\chapter{This and That}

\lipsum[2]

\end{document}

I know there are lot's of solutions on the web on how to write abstracts in the book class. I am mainly interested in the question why my solution of defining the environment technically doesn't work.

Best Answer

You are using \abstractname in the environment, but latex does not know it. This is the error you got. Hence defining it solves the issue. You have to define \abstractname by 

\newcommand\abstractname{Abstract}

Your MWE becomes:

\documentclass[11pt, a4paper]{book}

\usepackage{lipsum}
\newcommand\abstractname{Abstract}  %%% here
\makeatletter
\if@titlepage
  \newenvironment{abstract}{%
      \titlepage
      \null\vfil
      \@beginparpenalty\@lowpenalty
      \begin{center}%
        \bfseries \abstractname
        \@endparpenalty\@M
      \end{center}}%
     {\par\vfil\null\endtitlepage}
\else
  \newenvironment{abstract}{%
      \if@twocolumn
        \section*{\abstractname}%
      \else
        \small
        \begin{center}%
          {\bfseries \abstractname\vspace{-.5em}\vspace{\z@}}%
        \end{center}%
        \quotation
      \fi}
      {\if@twocolumn\else\endquotation\fi}
\fi
\makeatother

\begin{document}

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

\chapter{This and That}

\lipsum[2]

\end{document}
Related Question