slot {methods}

R Documentation

The Slots in an Object from a Formal Class

Description

These functions return or set information about the individual slots in an object.

Usage

object@name
object@name <- value

slot(object, name)
slot(object, name) <- value

slotNames(x)

Arguments

object	An object from a formally defined class.
name	The character-string name of the slot. The name must be a valid slot name: see Details below.
value

A new value for the named slot. The value must be valid for this slot in this object's class.

x	Either the name of a class or an object from that class. Print getClass(class) to see the full description of the slots.

Details

The "@" operator and the slot function extract or replace the formally defined slots for the object. The operator takes a fixed name, which can be unquoted if it is syntactically a name in the language. A slot name can be any non-empty string, but if the name is not made up of letters, numbers, and ".", it needs to be quoted.

In the case of the slot function, the slot name can be any expression that evaluates to a valid slot in the class definition. Generally, the only reason to use the functional form rather than the simpler operator is because the slot name has to be computed.

The definition of the class contains the names of all slots diretly and indirectly defined. Each slot has a name and an associated class. Extracting a slot returns an object from that class. Setting a slot first coerces the value to the specified slot and then stores it.

Unlike attributes, slots are not partially matched, and asking for (or trying to set) a slot with an invalid name for that class generates an error.

Author(s)

John Chambers

References

Chambers, J. M. (1998) Programming with Data, Springer.

The web page http://www.omegahat.org/RSMethods/index.html is the primary documentation.

See Also

@, Classes, Methods, getClass

Examples

## Not run: 
slot(myTrack, "x")
slot(myTrack, "y") <- log(slot(myTrack, "x"))

slotNames("track")

## End(Not run)

---