where argument can specify the environment in which to look
for the object in any of several ways: as an integer (the position in
search list); as the character string name of an
element in the search list; or as an
sys.frame to access the currently active
function calls). The
envir argument is an alternative way to
specify an environment, but is primarily there for back compatibility.
This function looks to see if the name
x has a value bound to
it in the specified environment. If
a value is not found for
x in the specified environment, the
enclosing frames of the environment are searched until the name
is encountered. See
environment and the ‘R
Language Definition’ manual for details about the structure of
environments and their enclosures.
inherits = TRUE is the default behaviour for R but not for S.
mode is specified then only objects of that type are sought.
mode may specify one of the collections
mode): any member of the
collection will suffice. (This is true even if a member of a
collection is specified, so for example
mode = "special" will
seek any type of function.)