\verb and
\begin{verbatim} have to assume that they are getting the
first look at the parameter text; if they aren’t, TeX has already
assigned category codes so that the verbatim command doesn’t have a
chance. For example:
will work (typesetting ‘\verb+\error+
\error’), but
\newcommand{\unbrace}[1]{#1}
\unbrace{\verb+\error+}
will not (it will attempt to execute \error). Other errors one
may encounter are ‘\verb ended by end of line’, or even the
rather more helpful ‘\verb illegal in command argument’. The
same sorts of thing happen with \begin{verbatim} …
\end{verbatim}:
\ifthenelse{\boolean{foo}}{%
\begin{verbatim}
foobar
\end{verbatim}
}{%
\begin{verbatim}
barfoo
\end{verbatim}
}
provokes errors like ‘File ended while scanning use of
\@xverbatim’, as \begin{verbatim} fails to see its
matching \end{verbatim}.
This is why the LaTeX book insists that verbatim
commands must not appear in the argument of any other command; they
aren’t just fragile, they’re quite unusable in any “normal” command
parameter,
regardless of \protection. (The \verb
command tries hard to detect if you’re misusing it; unfortunately, it
can’t always do so, and the error message is therefore not reliable as an
indication of problems.)
The first question to ask yourself is: “is \verb actually
necessary?”.
\texttt{your text} produces the same result
as \verb+your text+, then there’s no need of
\verb in the first place.
\verb to typeset a URL or email
address or the like, then the \url command from the
url will help: it doesn’t suffer from all the problems of
\verb, though it’s still not robust;
“typesetting URLs” offers advice here.
\verb into the argument of a boxing
command (such as \fbox), consider using the lrbox
environmen)t:
\newsavebox{\mybox}
...
\begin{lrbox}{\mybox}
\verb!VerbatimStuff!
\end{lrbox}
\fbox{\usebox{\mybox}}
\cprotect command (from the
package cprotect) might help. The package manages to make a
macro read a verbatim argument in a “sanitised” way by the simple
medium of prefixing the macro with \cprotect:
\cprotect\section{Using \verb|verbatim|}
The package (at the time this author tested it) was still under
development (though it does work in this simple case) and
deserves consideration in most cases; the package documentation gives
more details.
Another way out is to use one of “argument types” of the
\NewDocumentCommand command in the experimental LaTeX3 package
xparse:
\NewDocumentCommand\cmd{ m v m }{#1 `#2' #3}
\cmd{Command }|\furble|{ isn't defined}
Which gives us:
CommandThe “\furbleisn’t defined
m” tag argument specifies a normal mandatory argument,
and the “v” specifies one of these verbatim arguments.
As you see, it’s implanting a \verb-style command argument in the
argument sequence of an otherwise “normal” sort of command; that
‘|’
may be any old character that doesn’t
conflict with the content of the argument.
This is pretty neat (even if the verbatim is in an argument of its
own) but the downside is that xparse pulls in
the experimental LaTeX3 programming environment
(l3kernel) which is pretty big.
Other than the cprotect package, there are three partial
solutions to the problem:
\VerbatimFootnotes, which redefines the \footnotetext
command, and hence also the behaviour of the \footnote)
command, in such a way that you can include \verb commands in
its argument. This approach could in principle be extended to the
arguments of other commands, but it can clash with other packages:
for example, \VerbatimFootnotes interacts poorly with the
para option of the footmisc package.
The memoir class defines its \footnote command so that
it will accept verbatim in its arguments, without any supporting package.
\SaveVerb,
with a corresponding \UseVerb command, that allow you to save
and then to reuse the content of its argument; for details of this
extremely powerful facility, see the package documentation.
Rather simpler is the verbdef package, whose \verbdef
command defines a (robust) command which expands to the verbatim
argument given.
\texttt), consider using
\string. \texttt{my\string_name}
typesets the same as
\verb+my_name+, and will work in the argument of a command. It
won’t, however, work in a moving argument, and no amount of
\protection will make it work in
such a case.
A robust alternative is:
\chardef\us=`\_
...
\section{... \texttt{my\us name}}
Such a definition is ‘naturally’ robust; the construction
“<back-tick>\<char>” may be used for any
troublesome character (though it’s plainly not necessary for things
like percent signs for which (La)TeX already provides
robust macros).
This answer last edited: 2013-02-15
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