Elaborate the descriptions for onecmd(), precmd(), and postcmd() so they are
useful.
diff --git a/Doc/lib/libcmd.tex b/Doc/lib/libcmd.tex
index 834d16a..59d573f 100644
--- a/Doc/lib/libcmd.tex
+++ b/Doc/lib/libcmd.tex
@@ -22,7 +22,6 @@
key; it defaults to \kbd{Tab}. If \var{completekey} is not \code{None}
and \module{readline} is available, command completion is done
automatically.
-
\end{classdesc}
\subsection{Cmd Objects}
@@ -72,8 +71,11 @@
\end{methoddesc}
\begin{methoddesc}{onecmd}{str}
-Interpret the argument as though it had been typed in in
-response to the prompt.
+Interpret the argument as though it had been typed in response to the
+prompt. This may be overridden, but should not normally need to be;
+see the \method{precmd()} and \method{postcmd()} methods for useful
+execution hooks. The return value is a flag indicating whether
+interpretation of commands by the interpreter should stop.
\end{methoddesc}
\begin{methoddesc}{emptyline}{}
@@ -94,17 +96,26 @@
empty list.
\end{methoddesc}
-\begin{methoddesc}{precmd}{}
-Hook method executed just before the command line is interpreted, but
-after the input prompt is generated and issued. This
+\begin{methoddesc}{precmd}{line}
+Hook method executed just before the command line \var{line} is
+interpreted, but after the input prompt is generated and issued. This
method is a stub in \class{Cmd}; it exists to be overridden by
-subclasses.
+subclasses. The return value is used as the command which will be
+executed by the \method{onecmd()} method; the \method{precmd()}
+implementation may re-write the command or simply return \var{line}
+unchanged.
\end{methoddesc}
-\begin{methoddesc}{postcmd}{}
+\begin{methoddesc}{postcmd}{stop, line}
Hook method executed just after a command dispatch is finished. This
method is a stub in \class{Cmd}; it exists to be overridden by
-subclasses.
+subclasses. \var{line} is the command line which was executed, and
+\var{stop} is a flag which indicates whether execution will be
+terminated after the call to \method{postcmd()}; this will be the
+return value of the \method{onecmd()} method. The return value of
+this method will be used as the new value for the internal flag which
+corresponds to \var{stop}; returning false will cause interpretation
+to continue.
\end{methoddesc}
\begin{methoddesc}{preloop}{}