Wrap text to quote it later in the same document

Question

I was wondering if there's a way to do the following:

• to wrap an excerpt of text in an environment and to label it;
• to quote it (entirely) later in the same document, via a \ref command or similar.

By doing so, one could modify the wrapped text, without having to update all of the later references to it in the document.

I'm aware that a simple workaround would be to use \input{} both in the first and in the later occurrences of the wrapped sentence; I only wanted to know if there's something more specific.

More in detail, my purpose is to wrap some text that I have to cite in an answer letter to the reviewer of a submitted paper.

Suppose I wrote in a first version of the paper that:

it is clear that 2+2=5

Now the reviewer makes me pay attention to the fact that there's an error. I correct it and:

1 - in the revised version of the paper I write:

\wraptext{twoplustwo}{it is clear that 2+2=4}

provided that \wraptext{}{} is the command I was looking for;

2 - in the answer to the reviewer, I specify:

the error has been corrected, as you can see in the following reported excerpt:

\citewrappedtext{twoplustwo}

again provided that \citewrappedtext{} is the command to recall the excerpt.

This way, one can later modify again the sentence:

\wraptext{twoplustwo}{it is obvious that 2+2=4}

without having to correct the quotes, too.

Answer 1

While the answers "use a command" or "use an environment" seem to be obvious, here's a solution "with batteries included" (@GitHub, ZIP archive):

\documentclass{scrartcl}
\pagestyle{empty}

\newcommand\declquotedtext[2]{\expandafter\def\csname quotedtext@#1 \endcsname{#2}}
\newcommand\defquotedtext[2]{\declquotedtext{#1}{#2}#2}
\newcommand\usequotedtext[1]{\csname quotedtext@#1 \endcsname}

\begin{document}
  \defquotedtext{test}{This is a test text.}

  \declquotedtext{later}{And this is a text declared for later use.}

  This is something completely unrelated.

  \usequotedtext{test}

  \usequotedtext{later}
\end{document}

The command \defquotedtext will accept a label and contents, define the label (for use in \usequotedtext) and print the contents (to avoid repetition). As suggested by Ruben, \declquotedtext will do what \defquotedtext does, without printing the contents:

As usual with commands, be careful with spaces after \defquotedtext and \usequotedtext.

Actually, I assumed that this has been packaged somewhere...

With credits to: What exactly do \csname and \endcsname do?

Answer 2

Doing this with an environment is quite easy, by using environ.

The actual implementation depends on what you really have in mind. What I propose can even go in a secondary file that's \input at \begin{document}. The order of the text snippets is unimportant.

\documentclass{article}

\usepackage{environ}

\makeatletter
\NewEnviron{storequote}[1]{%
  \@ifundefined{storequote@\detokenize{#1}}
    {\global\expandafter
     \def\csname storequote@\detokenize{#1}\expandafter\endcsname
     \expandafter{\BODY}}
    {\@latex@error{storequote error: key `\detokenize{#1}' already used}{\@ehd}}%
}
\newcommand{\getstoredquote}[1]{%
  \@nameuse{storequote@\detokenize{#1}}%
}
\makeatother

\begin{document}

\begin{storequote}{funny}
This is a funny quotation.
\end{storequote}

\begin{storequote}{bad}
This is a bad quotation.
\end{storequote}

\begin{storequote}{funny}
This will raise an error.
\end{storequote}

Some text just to call ``\getstoredquote{bad}'' and
some other text for calling ``\getstoredquote{funny}''.
Enough.

\end{document}