R: Is 'method' the Name of an S3 Method?

isS3method {utils}

R Documentation

Is 'method' the Name of an S3 Method?

Description

Checks if method is the name of a valid / registered S3 method. Alternatively, when f and class are specified, it is checked if f is the name of an S3 generic function and paste(f, class, sep=".") is a valid S3 method.

Usage

isS3method(method, f, class, envir = parent.frame())

Arguments

`method`	a character string, typically of the form `"fn.class"`. If omitted, `f` and `class` have to be specified instead.
`f`	optional character string, typically specifying an S3 generic function. Used, when `method` is not specified.
`class`	optional character string, typically specifying an S3 class name. Used, when `method` is not specified.
`envir`	the `environment` in which the method and its generic are searched first, as in `getS3method()`.

Value

logical TRUE or FALSE

Examples

isS3method("t")           # FALSE - it is an S3 generic
isS3method("t.default")   # TRUE
isS3method("t.ts")        # TRUE
isS3method("t.test")      # FALSE
isS3method("t.data.frame")# TRUE
isS3method("t.lm")        # FALSE - not existing
isS3method("t.foo.bar")   # FALSE - not existing

## S3 methods with "4 parts" in their name:
ff <- c("as.list", "as.matrix", "is.na", "row.names", "row.names<-")
for(m in ff) if(isS3method(m)) stop("wrongly declared an S3 method: ", m)
(m4 <- paste(ff, "data.frame", sep="."))
for(m in m4) if(!isS3method(m)) stop("not an S3 method: ", m)