handle
object to see if it is currently in use by the
handle management code.
handle.inuse(x)
handle
object.
TRUE
if the given
handle
is considered to be "inuse". Returns
FALSE
otherwise.
The code that maintains the handles keeps track of an "inuse" flag for
each handle. The intent is that a handle would be "inuse" while it refers
to resources that are still being used, such as file descriptors and a
process ID number for an external process. If that process were
terminated, the corresponding handle would be marked as no longer in use
with the
handle.free
function.
if(!handle.inuse(current.handle)) rm(current.handle)