R: Examples for 'methods::GenericFunctions'

### ** Examples

require(stats) # for lm

## get the function "myFun" -- throw an error if 0 or > 1 versions visible:
findFuncStrict <- function(fName) {
  allF <- findFunction(fName)
  if(length(allF) == 0)
    stop("No versions of ",fName," visible")
  else if(length(allF) > 1)
    stop(fName," is ambiguous: ", length(allF), " versions")
  else
    get(fName, allF[[1]])
}

try(findFuncStrict("myFun"))# Error: no version

Error in findFuncStrict("myFun") : No versions of myFun visible

lm <- function(x) x+1
try(findFuncStrict("lm"))#    Error: 2 versions

function (formula, data, subset, weights, na.action, method = "qr", 
    model = TRUE, x = FALSE, y = FALSE, qr = TRUE, singular.ok = TRUE, 
    contrasts = NULL, offset, ...) 
{
    ret.x <- x
    ret.y <- y
    cl <- match.call()
    mf <- match.call(expand.dots = FALSE)
    m <- match(c("formula", "data", "subset", "weights", "na.action", 
        "offset"), names(mf), 0L)
    mf <- mf[c(1L, m)]
    mf$drop.unused.levels <- TRUE
    mf[[1L]] <- quote(stats::model.frame)
    mf <- eval(mf, parent.frame())
    if (method == "model.frame") 
        return(mf)
    else if (method != "qr") 
        warning(gettextf("method = '%s' is not supported. Using 'qr'", 
            method), domain = NA)
    mt <- attr(mf, "terms")
    y <- model.response(mf, "numeric")
    w <- as.vector(model.weights(mf))
    if (!is.null(w) && !is.numeric(w)) 
        stop("'weights' must be a numeric vector")
    offset <- model.offset(mf)
    mlm <- is.matrix(y)
    ny <- if (mlm) 
        nrow(y)
    else length(y)
    if (!is.null(offset)) {
        if (!mlm) 
            offset <- as.vector(offset)
        if (NROW(offset) != ny) 
            stop(gettextf("number of offsets is %d, should equal %d (number of observations)", 
                NROW(offset), ny), domain = NA)
    }
    if (is.empty.model(mt)) {
        x <- NULL
        z <- list(coefficients = if (mlm) matrix(NA_real_, 0, 
            ncol(y)) else numeric(), residuals = y, fitted.values = 0 * 
            y, weights = w, rank = 0L, df.residual = if (!is.null(w)) sum(w != 
            0) else ny)
        if (!is.null(offset)) {
            z$fitted.values <- offset
            z$residuals <- y - offset
        }
    }
    else {
        x <- model.matrix(mt, mf, contrasts)
        z <- if (is.null(w)) 
            lm.fit(x, y, offset = offset, singular.ok = singular.ok, 
                ...)
        else lm.wfit(x, y, w, offset = offset, singular.ok = singular.ok, 
            ...)
    }
    class(z) <- c(if (mlm) "mlm", "lm")
    z$na.action <- attr(mf, "na.action")
    z$offset <- offset
    z$contrasts <- attr(x, "contrasts")
    z$xlevels <- .getXlevels(mt, mf)
    z$call <- cl
    z$terms <- mt
    if (model) 
        z$model <- mf
    if (ret.x) 
        z$x <- x
    if (ret.y) 
        z$y <- y
    if (!qr) 
        z$qr <- NULL
    z
}
<bytecode: 0x55ccfcae9b68>
<environment: namespace:stats>

findFuncStrict("findFuncStrict")# just 1 version

Error in findFuncStrict("findFuncStrict"): No versions of findFuncStrict visible

rm(lm)

## Don't show: 
## because nosegfault runs standardGeneric w/o the methods package, nothing
## really gets tested.  The following check that it catches some errors
mustDie <- function(expr)
   stopifnot(is(tryCatch(expr, error=function(e)e), "error"))

mustDie(standardGeneric()) # 3 tests of requiring a single string
mustDie(standardGeneric(NULL))
mustDie(standardGeneric(""))
mustDie(standardGeneric("notAGenericFunction"))
mustDie(standardGeneric("show"))  # a generic, but not called from its body
## End(Don't show)

## method dumping ------------------------------------

setClass("A", slots = c(a="numeric"))
setMethod("plot", "A", function(x,y,...){ cat("A meth\n") })
dumpMethod("plot","A", file="")

setMethod("plot", "A",
function (x, y, ...) 
{
    cat("A meth\n")
}
)

## Not run: 
##D setMethod("plot", "A",
##D function (x, y, ...)
##D {
##D     cat("AAAAA\n")
##D }
##D )
## End(Not run)
tmp <- tempfile()
dumpMethod("plot","A", file=tmp)
## now remove, and see if we can parse the dump
stopifnot(removeMethod("plot", "A"))
source(tmp)
stopifnot(is(getMethod("plot", "A"), "MethodDefinition"))

## same with dumpMethods() :
setClass("B", contains="A")
setMethod("plot", "B", function(x,y,...){ cat("B ...\n") })
dumpMethods("plot", file=tmp)
stopifnot(removeMethod("plot", "A"),
          removeMethod("plot", "B"))
source(tmp)
stopifnot(is(getMethod("plot", "A"), "MethodDefinition"),
          is(getMethod("plot", "B"), "MethodDefinition"))

Examples for 'methods::GenericFunctions'

Tools for Managing Generic Functions