How to make a new environment behave like an existing environment? (Part 2: endnotes and comments)

Question

In a previous post i mentioned my attempt to create an environment that behaves alternately like a footnote, an endnote or a comment (i.e. hidden). Thanks to the help of those who answered the above mentioned question, i am now able to define a new environment that behaves like the footnote environment by employing one of the following two technique:

\documentclass{article}
\usepackage{environ}
\NewEnviron{mynote}{\footnote{\BODY}}
\begin{document}
Hello\begin{mynote}world\end{mynote}
\end{document}

or equivalently

\documentclass{article}
\newenvironment{mynote}{\footnote\bgroup}{\egroup}
\begin{document}
Hello\begin{mynote}world\end{mynote}.
\end{document}

Unfortunately, what works for footnotes fails for endnotes and comments. The following two blocks of code (the first for endnotes using the second technique and the second for comments using the first technique), don't even compile.

\documentclass{article}
\usepackage{endnotes}
\newenvironment{mynote}{\endnote\bgroup}{\egroup}
\begin{document}
Hello\begin{mynote}world\end{mynote}.
\theendnotes
\end{document}

\documentclass{article}
\usepackage{comment}
\usepackage{environ}
\NewEnviron{mynote}{\begin{comment}\BODY\end{comment}}
\begin{document}
Hello\begin{mynote}world\end{mynote}
\end{document}

Why do the techniques that work for footnotes fail for endnotes and comments? What can i do about it?

Answer 1

I don't see why using an environment. My best shot would be using a command.

\documentclass{article}
\usepackage{endnotes}

\makeatletter
% p for `perhaps'
\newcommand{\pfootnote}{\csname aad@footnote@\aad@footnotekind\endcsname}
\newcommand{\footnotekind}[1]{\def\aad@footnotekind{#1}}

\let\aad@footnote@footnote\footnote
\let\aad@footnote@endnote\endnote
\newcommand\aad@footnote@comment[2][]{}
\def\aad@footnotekind{footnote} % default
\makeatother

%% footnotes are footnotes
\footnotekind{footnote}

\begin{document}

Hello\pfootnote{world}

\footnotekind{endnote}

Hello\pfootnote{world}

\footnotekind{comment}

Hello\pfootnote{world}

\bigskip
\hrule
\bigskip

\theendnotes

\end{document}

Of course you won't be changing the kind of footnotes in the middle of the document; you'll probably set one among

\footnotekind{footnote}
\footnotekind{endnote}
\footnotekind{comment}

the first being the default (but I used it in the preamble for greater clarity).

(Note: the height of the example image has been artificially reduced just for showing the result.)

If you really want an environment, add to the above macros also

\usepackage{environ}
\NewEnviron{mynote}{\expandafter\pfootnote\expandafter{\BODY}}

---

A version that automatically adds the endnotes if \footnotekind{endnote} is issued. Something is added to be executed \AtEndDocument; in case footnotes or comments are chosen, this will be nothing because the corresponding sequence is not defined.

\documentclass{article}
\usepackage{endnotes}

\makeatletter
% p for `perhaps'
\newcommand{\pfootnote}{\csname aad@footnote@\aad@footnotekind\endcsname}
\newcommand{\footnotekind}[1]{%
  \def\aad@footnotekind{#1}%
  \AtEndDocument{\@nameuse{aad@footnoteatend@#1}}%
}

\let\aad@footnote@footnote\footnote
\let\aad@footnote@endnote\endnote
\newcommand\aad@footnote@comment[2][]{}
\def\aad@footnoteatend@endnote{\theendnotes}

\def\aad@footnotekind{footnote} % default
\makeatother

%% footnotes are endnotes
\footnotekind{endnote}

\begin{document}

Hello\pfootnote{world}

Hello\pfootnote{world again}

Hello\pfootnote{world and again}

\end{document}