Problems using hooks

Question

I am trying to duplicate a document using hooks at the beginning and the end. Here is a minimal example of my problem :

\documentclass{minimal}

\usepackage{environ}
\usepackage{forloop}

%Repeat text
\newcounter{loopcntr}
\newcommand{\rpt}[1]{
\forloop{loopcntr}{0}{\value{loopcntr}<2}{#1}
}

%Create an environment to repeat text
\NewEnviron{rptenv}{
    \rpt{\BODY}
}

\AtBeginDocument{
    \begin{rptenv}
}

\AtEndDocument{
    \end{rptenv}
}

\begin{document}
Hello.
\end{document}

Why doesn't it work ? If I replace "rptenv" in the hooks by "center", it works like a charm. Is there another way to achieve an automated repetition without changing anything in the body of the file ?

It won't work. Your environment needs to find the string \end{rptenv} to stop the parsing. You can't hide it in \end{document}. http://tex.stackexchange.com/questions/218589/runaway-argument-error-with-newenviron. I would put the content of the document in some external file and do the loop over \input{content}. — Ulrike Fischer, Aug 27 '15 at 15:13
@touhami I forgot to change that to do my minimal example. I made the change. — fyusuf-a, Aug 27 '15 at 15:56

score 1 · Accepted Answer · answered Aug 27 '15 at 16:40

The following seems to work with some tricks:

\documentclass{minimal}

\usepackage{environ}
\usepackage{forloop}

%Repeat text
\newcounter{loopcntr}
\newcommand{\rpt}[1]{
  \forloop{loopcntr}{0}{\value{loopcntr}<3}{#1}
}

%Create an environment to repeat text
\NewEnviron{rptenv}{%
    \rpt{\BODY}%
}

\makeatletter
\g@addto@macro\document{%
    \rptenv
}
\makeatother

\begin{document}
Hello.
\end{document}

\begin{rptenv} does not work inside another environment, because the environment name is used to find the \end{...} part.

The preamble is not yet finished, when the \AtBeginDocument hook is called, therefore the part after the hook of \begin{document} must not be called twice. This is fixed in the example by appending \rptenv to the command form \document.

I have dropped, \endrptenv, because it is not needed here (it would expand to \ignorespacesafterend, but the job is finished by \end{document}, thus spaces afterwards do not matter).

Problems using hooks

1 Answers1