\Header{sys.parent}{Functions to access the function call stack.}
\alias{sys.call}{sys.parent}
\alias{sys.calls}{sys.parent}
\alias{sys.frame}{sys.parent}
\alias{sys.frames}{sys.parent}
\alias{sys.nframe}{sys.parent}
\alias{sys.function}{sys.parent}
\alias{sys.parents}{sys.parent}
\alias{sys.on.exit}{sys.parent}
\alias{sys.status}{sys.parent}
\keyword{programming}{sys.parent}
\keyword{data}{sys.parent}
\begin{Usage}
\begin{verbatim}
sys.call(which=<<see below>>)
sys.frame(which=<<see below>>)
sys.nframe()
sys.function(n=<<see below>>)
sys.parent(n=1)

sys.calls()
sys.frames()
sys.parents()
sys.on.exit()
sys.status()
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\texttt{which}] the frame number.
\item[\texttt{n}] the number of frame generations to go back.
\end{ldescription}
\end{Arguments}
\begin{Description}
These functions provide access to \texttt{\Link{environment}}s (``frames''
in S-speak) associated with functions further up the calling stack.\end{Description}
\begin{SeeAlso}
\texttt{\Link{eval}} for the usage of \texttt{sys.frame}.\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
ff <- function(x) gg(x)
gg <- function(y) sys.status()
str(ff(1))
\end{ExampleCode}
\end{Examples}

