The R Project SVN R

first argument and nothing else.

first argument and nothing else.

In this case,

In this case,

the recommended approach is to define the S3 method and also supply the

the recommended approach is to define the S3 method and also supply the

identical function as the definition of the S4 method.

identical function as the definition of the S4 method.

If the S3 generic function was \code{f3(x, ...)} and the S4 class for

If the S3 generic function was \code{f3(x, ...)} and the S4 class for

\code{"myClass"}:

\code{"myClass"}:

 \code{f3.myClass <- function(x, ...) { ..... }}

 \code{f3.myClass <- function(x, ...) { ..... }}

 \code{setMethod("f3", "myClass", f3.myClass)}

 \code{setMethod("f3", "myClass", f3.myClass)}

Two additional mechanisms for defining

Two additional mechanisms for defining

superclasses exist.

superclasses exist.

A call to \code{\link{setClassUnion}} creates a union class that

A call to \code{\link{setClassUnion}} creates a union class that

is a

is a

superclass of each of the members of the union.

superclass of each of the members of the union.

\code{\link{setIs}} can create an inheritance relationship that is not the simple one of

\code{\link{setIs}} can create an inheritance relationship that is not the simple one of

containing the superclass representation in the new class.

containing the superclass representation in the new class.

Arguments \code{coerce} and \code{replace} supply methods to convert

Arguments \code{coerce} and \code{replace} supply methods to convert

to the superclass and to replace the part corresponding to the superclass.

to the superclass and to replace the part corresponding to the superclass.

(In addition, a \code{test=} argument allows conditional inheritance;  conditional inheritance is not

(In addition, a \code{test=} argument allows conditional inheritance;  conditional inheritance is not

A call to a generic function therefore has two contexts:  one for the

A call to a generic function therefore has two contexts:  one for the

function and a second for the method.

function and a second for the method.

The argument objects will be copied to the second context, but not any

The argument objects will be copied to the second context, but not any

local objects created in a nonstandard generic function.

local objects created in a nonstandard generic function.

(\dQuote{enclosing}) environment of the second context is the environment

(\dQuote{enclosing}) environment of the second context is the environment

of the method as a function, so that all \R programming techniques

of the method as a function, so that all \R programming techniques

using such environments apply to method definitions as ordinary functions.

using such environments apply to method definitions as ordinary functions.

## a method explicitly for "myFrame" class

## a method explicitly for "myFrame" class

setMethod("[",

setMethod("[",

    signature(x = "myFrame"),

    signature(x = "myFrame"),

    {

    {

        S3Part(x) <- callNextMethod()

        S3Part(x) <- callNextMethod()

        x@timestamps <- c(Sys.time(), as.POSIXct(x@timestamps))

        x@timestamps <- c(Sys.time(), as.POSIXct(x@timestamps))

        x

        x

    }

    }