Removing character from a hyperref link

Question

I would like to suppress a character from a hyperref link that is built via \url, but the textual representation should keep that character. For example, if the character is *, I want \url{http://tex.stackexchange*.com} act as \href{http://tex.stackexchange.com}{http://tex.stackexchange*.com}.

An embarrassingly failing attempt to hack the \hyper@linkurl macro is given in the MWE, just to show some effort.

\documentclass{article}
\usepackage{hyperref}
\begin{document}
\makeatletter
\renewcommand\hyper@linkurl{%
  \begingroup
    \lccode`\~=`\*\relax
    \lowercase{\def~}{}%
    \catcode`\*\active
    \lccode`\~=0\relax
    \my@hyper@linkurl
}
\def\my@hyper@linkurl#1#2{%
   \edef\x{\toks0={#2}}\x
   \Hy@pstringdef\Hy@pstringURI{\the\toks0}%
   \hyper@chars
   \leavevmode
    \pdfstartlink
      attr{%
        \Hy@setpdfborder
        \ifx\@pdfhightlight\@empty
        \else
          /H\@pdfhighlight
        \fi
        \ifx\@urlbordercolor\relax
        \else
          /C[\@urlbordercolor]%
        \fi
      }%
      user{%
       /Subtype/Link%
       \ifHy@pdfa /F 4\fi
       /A<<%
         /Type/Action%
         /S/URI%
         /URI(\Hy@pstringURI)%
         \ifHy@href@ismap
           /IsMap true%
         \fi
         \Hy@href@nextactionraw
       >>%
      }%
      \relax
    \Hy@colorlink\@urlcolor#1\Hy@xspace@end
    \close@pdflink
  \endgroup
}
\makeatother
\url{http://tex.stackexchange*.com}
\end{document}

This is trying to make the star active, and let it be replaced by an empty group in the assignment to toks0, but it does not work. It also does not feel right to replicate so much code from hyperref. What is a better way to achieve this?

Answer 1

With the etoolbox package, patching of \hyper@linkurl seems easy and is more reliable than the my custom \URL definition (see a previous version of this answer).

This allows to use # and & in URLs.

Code

\documentclass{article}
\usepackage{hyperref}
\usepackage{etoolbox}
\makeatletter
\def\strip@star#1*#2\@strip@star{%
    \expandafter\def\expandafter\strip@star@result\expandafter{\strip@star@result#1}%
    \if\relax\detokenize{#2}\relax\else
        \def\strip@star@temp{#2}%
        \expandafter\expandafter\expandafter\strip@star\expandafter\strip@star@temp
        \expandafter\@strip@star
    \fi
}
\patchcmd{\hyper@linkurl}{\Hy@pstringdef\Hy@pstringURI{#2}}{%
    \def\strip@star@result{}%
    \expandafter\strip@star#2*\@strip@star
    \Hy@pstringdef\Hy@pstringURI{\strip@star@result}%
}{}{}
\makeatother

\begin{document}
\url{http://tex*.stack*exchange*.com#anchorwithfun:$&}
\end{document}

Output