The LaTeX verbatim commands work by changing category codes. Knuth
says of this sort of thing “Some care is needed to get the timing
right…”, since once the category code has been assigned to a
character, it doesn’t change. So \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 if we define no more than a
no-op macro,
\newcommand{\unbrace}[1]{#1}
which simply regurgitates its argument, and use it as:
\unbrace{\verb+\error+}
the combinartion 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
environment:
\newsavebox{\mybox}
...
\begin{lrbox}{\mybox}
\verb!VerbatimStuff!
\end{lrbox}
\fbox{\usebox{\mybox}}
If you can’t avoid verbatim, the \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 does work in this simple case, and deserves
consideration in many others 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:
Command \furble isn’t defined
The “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 four 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; the newverbs package provides a similar
function as well as several related ones.
\begin{verbbox}
some exotic _&$ stuff
\end{verbbox}
\theverbbox
the operation typesets exotic stuff into an anonymous box, and its
contents may be retrieved using the command \theverbbox. It is
clear that it’s in the same mould as the \verbdef command
mentioned above; the package defines other similar commands.
\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).
\begin{tcbverbatimwrite}{}
...
\end{tcbverbatimwrite}
which (as one might guess) writes to the named file; load the saved
contents using \input{}
A second environment puts your verbatim material in an (apparently) anonymous temporary file:
\begin{tcbwritetemp}{}
...
\end{tcbverbatimwrite}
In this case, you use the anonymous file with the \tcbusetemp
macro. (You can change the name used for the ‘anonymous’ file, if
its default proves troublesome.)
The moreverb package provides a \verbatimwrite
command, which doesn’t provide an anonynous file.
Macros, to achieve the same effect, are outlined in the documentation of the verbatim package; the macros use the facilities of the package, but the user has to write a mini-package actually to use them.
This answer last edited: 2013-10-21
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