Changing href's to footnotes

Here is exactly what I am trying to do. I have a file with many commands of the form \href{a}{b} for strings a and b. I would like to redefine \href so that it executes the following: \footnote{\href{a}{b}}. Thus want to change the URL's into footnotes to URL's. – Is this possible?

This can be done using the standard \let technique:

\let\oldhref=\href
\renewcommand{\href}[2]{\footnote{\oldhref{#1}{#2}}}

• Completing Andrey's answer: \let\oldhref\href saves the current meaning of \href. You can then use this old version of \href in the new definition of \href. jrhorn424's solution below would cause an infinite loop as Joseph says below: \href{a}{b} would expand to \footnote{\href{a}{b}}, and the \href in there would expand to \footnote{\href{a}{b}}, etc. – Bruno Le Floch Mar 6 '11 at 17:18
• This does not work if the second argument contains active characters. Try \href{Test}{http://www.test.com/a=3&b=5}. – Michael Ummels Jul 23 '11 at 12:36

This solution also works with URLs that include active characters such as &, % and # (requires hyperref):

\makeatletter
\DeclareRobustCommand{\hreffootnote}{\hyper@normalise\hreffootnote@}
\makeatother

However, as far as I understand your blog post, you actually want that \href{a}{b} behaves like b\footnote{\url{a}}. This can be achieved as follows:

\makeatletter
\newcommand\myhref@[2]{#2\footnote{\url@{#1}}}
\DeclareRobustCommand{\myhref}{\hyper@normalise\myhref@}
\makeatother

Also, see my answer to this question.

The first argument of \href must be handled as verbatim which makes redefinitions tricky. Michael Ummels's answer correctly shows how to use hyperrefs internal macros for this. However, the recent update of my newverbs package provides a way to collect an argument verbatim easily:

\documentclass{article}

\usepackage{hyperref}
\usepackage{newverbs}[2011/07/24]

\let\orighref\href
\renewcommand{\href}{\Collectverb{\hrefii}}
\newcommand\hrefii[2]{\footnote{\orighref{#1}{#2}}}

\usepackage{lipsum}% Dummy text
\begin{document}

\lipsum*[1]\href{http://test.com/%$^£$%^_@~}{Test URL}

% With other argument separators as { }:
\lipsum*[2]\href|http://test.com/%$^£$}{%^_@~|{Test URL}

% If a real \href is wanted (also used for comparison here)
\lipsum*[3]\orighref{http://test.com/%$^£$%^_@~}{Test URL}

\end{document}

• You should disclose that you're the author of newverbs. – lockstep Jul 27 '11 at 5:06
• @lockstep: Done. I'm never sure about it. When I mention it's my package it sounds like advertising and if I don't, it looks like hidden advertising :-) – Martin Scharrer Jul 27 '11 at 7:30