Using commands inside \url?

Question

How does one use commands inside \url{..}?

MWE:

\documentclass{article}
\usepackage{textcomp}   
\usepackage{xcolor}
\usepackage{url}

\newcommand{\placeholder}[1]{\textcolor{red!60!black}{\textlangle#1\textrangle}}

\begin{document}
\url{Hello \placeholder{name}}.
\end{document}

which produces:

Hello \placeholder{name}.

and not the expected:

Hello <name>.

This is a contrived example. In reality I have defined several custom url commands (Macros for formatting & breaking classnames, file paths etc?), and it is in those commands that I want to use the placeholder. But I believe the solution for this simpler case is the same as for the custom urlcommands.

Answer 1

\UrlLeft and \UrlRight can be used for the purpose of adding angle brackets, see section "6 Yet more flexibility" url's documentation. Example:

\documentclass{article}

\usepackage{url}
\DeclareUrlCommand\url{%
  \def\UrlLeft{\langle}%
  \def\UrlRight{\rangle}%
}

\begin{document}
  \url{http://www.example.org/}
\end{document}

Remarks:

• \langle and \rangle are used instead of the text mode commands, because the implicitly used math mode of \url.

Package hyperref

Command \url is redefined to add additional code needed by hyperref, thus it cannot be redefined directly. The old meaning is stored and uses as \Hurl, thus this is the macro that can be redefined:

\documentclass{article}

\usepackage[colorlinks]{hyperref}% loads package url
\DeclareUrlCommand\Hurl{%
  \def\UrlLeft{\langle}%
  \def\UrlRight{\rangle}%
}

\begin{document}
  \url{http://www.example.org/}
\end{document}

The angle brackets are part of the link, but not part of the URL for the link. If the brackets should not be colorized by option colorlinks, then the color could be reset to \normalcolor for the fences:

\documentclass{article}

\usepackage[colorlinks]{hyperref}% loads package url
\DeclareUrlCommand\Hurl{%
  \def\UrlLeft{\begingroup\normalcolor\langle\endgroup}%
  \def\UrlRight{\begingroup\normalcolor\rangle\endgroup}%
}

\begin{document}
  \url{http://www.example.org/}
\end{document}

If the current color should be used instead of \normalcolor, then it becomes a little more complicate. Package xcolor has the concept of a current color . and this color can be saved via \colorlet and uses later inside the url command:

\documentclass{article}

\usepackage{xcolor}
\usepackage{letltxmacro}
\usepackage[colorlinks]{hyperref}% loads package url

\LetLtxMacro\OriginalUrl\url
\DeclareRobustCommand*{\url}{%
  \colorlet{beforeurl}{.}%
  \OriginalUrl
}
\DeclareUrlCommand\Hurl{%
  \def\UrlLeft{\begingroup\color{beforeurl}\langle\endgroup}%
  \def\UrlRight{\begingroup\color{beforeurl}\rangle\endgroup}%
}

\begin{document}
  \color{blue}\url{http://www.example.org/}
\end{document}

Answer 2

Not sure I understand the requirements, but here is some custom \verb more or less extracted from some code I needed on another occasion. As the alltt environment from the alltt package it treats \, {, and } normally. Additionally it treats spaces as in regular tex source, thus allowing line breaks. And this is an inline, not display "environment".

To be used as \myverb!stuff! or \myverb+stuff+ etc... (no empty line in argument, to force multiple spaces, use \ \ \ for example as in standard text).

\documentclass{article}
\usepackage{xcolor}
\usepackage{textcomp}

\makeatletter
% DEFINITIONS FOR SOME CUSTOM INLINE VERBATIM À LA ALLTT
% customize as desired:
\def\MicroFont{\normalfont\ttfamily\hyphenchar\font 45 }

\def\mydo@noligs #1% 
% jfbu: modification to \do@noligs  (added space after `#1) is mandatory if
% space is not made active via \@vobeyspaces in verbatim stuff.
{%
    \catcode `#1\active 
    \begingroup \lccode `\~=`#1\relax 
    \lowercase {\endgroup \def ~{\leavevmode \kern \z@ \char `#1 }}%
}%

% custom inline verbatim allowing line-breaks and like in alltt environment, \,
% { and } have their standard behavoir. For example an hyphenation point may be
% added with \-. NOTA BENE: spaces are treated as elsewhere, thus multiple
% spaces in source collapsed into only one in printed result. Line breaks are
% possible. 
\def\myverb 
{%
  \relax \ifmmode\hbox\else\leavevmode\null\fi
  \bgroup \MicroFont
  \let\do\mydo@noligs  \verbatim@nolig@list
  \let\do\@makeother   \dospecials 
  \catcode32 10 
  \catcode92 0 \catcode123 1 \catcode125 2
  \frenchspacing
  \@myverb 
}% 
\def\@myverb #1{\catcode`#1\active\lccode`\~`#1\lowercase{\let~\egroup}}%

\makeatother

\newcommand{\placeholder}[1]{\textcolor{red!60!black}{\textlangle#1\textrangle}}

\begin{document}\thispagestyle{empty}
\myverb+Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}
Hello \placeholder{name}+ and this works also in math mode $a^n
+\myverb?b^n=c^n?$. Back to normal.
\end{document}

---

I would try

\newcommand{\urlholder}[1]{\textcolor{red!60!black}{\textlangle\url{#1}\textrangle}}

mwe:

\documentclass{article}
\usepackage{textcomp}   
\usepackage{xcolor}
\usepackage{url}

\newcommand{\urlholder}[1]{\textcolor{red!60!black}{\textlangle\url{#1}\textrangle}}

\begin{document}

Hello \urlholder{name and \name}

\end{document}