\HeaderA{ns-load}{Loading and Unloading Name Spaces}{ns.Rdash.load}
\aliasA{attachNamespace}{ns-load}{attachNamespace}
\aliasA{loadedNamespaces}{ns-load}{loadedNamespaces}
\aliasA{loadNamespace}{ns-load}{loadNamespace}
\aliasA{unloadNamespace}{ns-load}{unloadNamespace}
\keyword{data}{ns-load}
\keyword{utilities}{ns-load}
\begin{Description}\relax
Functions to load and unload namespaces.
\end{Description}
\begin{Usage}
\begin{verbatim}
attachNamespace(ns, pos = 2, dataPath = NULL)
loadNamespace(package, lib.loc = NULL,
              keep.source = getOption("keep.source.pkgs"),
              partial = FALSE, declarativeOnly = FALSE)
loadedNamespaces()
unloadNamespace(ns)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{ns}] string or namespace object.
\item[\code{pos}] integer specifying position to attach.
\item[\code{dataPath}] path to directory containing a database of datasets to
be lazy-loaded into the attached environment.
\item[\code{package}] string naming the package/name space to load.
\item[\code{lib.loc}] character vector specifying library search path.
\item[\code{keep.source}] logical specifying whether to retain source.
This applies only to the specified name space, and not to other name spaces
which might be loaded to satisfy imports.

For more details see this argument to \code{\LinkA{library}{library}}.

\item[\code{partial}] logical; if true, stop just after loading code.
\item[\code{declarativeOnly}] logical; disables \code{.Import}, etc, if true.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The functions \code{loadNamespace} and \code{attachNamespace} are
usually called implicitly when \code{library} is used to load a name
space and any imports needed.  However it may be useful to call
these functions directly at times.

\code{loadNamespace} loads the specified name space and registers it in
an internal data base.  A request to load a name space that is already
loaded has no effect.  The arguments have the same meaning as the
corresponding arguments to \code{\LinkA{library}{library}}, whose help page
explains the details of how a particular installed package comes to be
chosen.  After loading,
\code{loadNamespace} looks for a hook function named
\code{\LinkA{.onLoad}{.onLoad}} as an internal variable in the name space (it
should not be exported).  This function is called with the same arguments
as \code{.First.lib}.  Partial loading is used to support installation with
the \option{--save} and \option{--lazy} options.

\code{loadNamespace} does not attach the name space it loads to the
search path.  \code{attachNamespace} can be used to attach a frame
containing the exported values of a name space to the search path.
The hook function \code{\LinkA{.onAttach}{.onAttach}} is run after the name space
exports are attached.

\code{loadedNamespaces} returns a character vector of the names of
the loaded name spaces.

\code{unloadNamespace} can be used to force
a name space to be unloaded.  An error is signaled if the name space
is imported by other loaded name spaces.  If defined, a hook
function \code{\\code\{.onUnload\}} is run
before removing the name space from the internal registry.
\code{unloadNamespace} will first \code{\LinkA{detach}{detach}} a package of
the same name if one is on the path, thereby running a
\code{.Last.lib} function in the package if one is exported.
\end{Details}
\begin{Author}\relax
Luke Tierney
\end{Author}

