\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 when one of
that name 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 attempt to force a name space to
be unloaded.  If the namespace is attached, it is first
\code{\LinkA{detach}{detach}}ed, thereby running a \code{.Last.lib} function
in the namespace if one is exported.  Then an error is signaled if the
name space is imported by other loaded name spaces, and the namespace
is not unloaded.  If defined, a hook function \code{\LinkA{.onUnload}{.onUnload}}
is run before removing the name space from the internal registry.
\end{Details}
\begin{Value}
\code{attachNamespace} returns invisibly the environment it adds to
the search path.

\code{loadNamespace} returns the namespace environment, either one
already loaded or the one the function causes to be loaded.

\code{loadedNamespaces} returns a character vector.

\code{unloadNamespace} returns \code{NULL}, invisibly.
\end{Value}
\begin{Author}\relax
Luke Tierney
\end{Author}

