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> ####--- S4 Methods (and Classes)  --- see also ../src/library/methods/tests/
> options(useFancyQuotes=FALSE)
> require(methods)
> ##too fragile: showMethods(where = "package:methods")
> 
> ##-- S4 classes with S3 slots [moved from ./reg-tests-1.R]
> setClass("test1", representation(date="POSIXct"))
[1] "test1"
> x <- new("test1", date=as.POSIXct("2003-10-09"))
> stopifnot(format(x @ date) == "2003-10-09")
> ## line 2 failed in 1.8.0 because of an extraneous space in "%in%"
> 
> stopifnot(all.equal(3:3, 3.), all.equal(1., 1:1))
> 
> ## trace (requiring methods):
> f <- function(x, y) { c(x,y)}
> xy <- 0
> trace(f, quote(x <- c(1, x)), exit = quote(xy <<- x), print = FALSE)
[1] "f"
> fxy <- f(2,3)
> stopifnot(identical(fxy, c(1,2,3)))
> stopifnot(identical(xy, c(1,2)))
> untrace(f)
> 
> ## a generic and its methods
> 
> setGeneric("f")
[1] "f"
> setMethod("f", c("character", "character"), function(x,    y) paste(x,y))
[1] "f"
> 
> ## trace the generic
> trace("f", quote(x <- c("A", x)), exit = quote(xy <<- c(x, "Z")), print = FALSE)
[1] "f"
> 
> ## should work for any method
> 
> stopifnot(identical(f(4,5), c("A",4,5)),
+           identical(xy, c("A", 4, "Z")))
> 
> stopifnot(identical(f("B", "C"), paste(c("A","B"), "C")),
+           identical(xy, c("A", "B", "Z")))
> 
> ## trace a method
> trace("f", sig = c("character", "character"), quote(x <- c(x, "D")),
+       exit = quote(xy <<- xyy <<- c(x, "W")), print = FALSE)
[1] "f"
> 
> stopifnot(identical(f("B", "C"), paste(c("A","B","D"), "C")))
> stopifnot(identical(xyy, c("A", "B", "D", "W")))
> # got broken by Luke's lexical scoping fix:
> #stopifnot(identical(xy, xyy))
> 
> ## but the default method is unchanged
> stopifnot(identical(f(4,5), c("A",4,5)),
+           identical(xy, c("A", 4, "Z")))
> 
> removeGeneric("f")
[1] TRUE
> ## end of moved from trace.Rd
> 
> 
> ## print/show dispatch  [moved from  ./reg-tests-2.R ]
> ## The results  have waffled back and forth.
> ## Currently (R 2.4.0) the intent is that automatic printing of S4
> ## objects should correspond to a call to show(), as per the green
> ## book, p. 332.  Therefore, the show() method is called, once defined,
> ## for auto-printing foo, regardless of the S3 or S4 print() method.
> ## (But most of this example is irrelevant if one avoids S3 methods for
> ## S4 classes, as one should.)
> setClass("bar", representation(a="numeric"))
[1] "bar"
> foo <- new("bar", a=pi)
> foo
An object of class "bar"
Slot "a":
[1] 3.141593

> show(foo)
An object of class "bar"
Slot "a":
[1] 3.141593

> print(foo)
An object of class "bar"
Slot "a":
[1] 3.141593

> 
> setMethod("show", "bar", function(object){cat("show method\n")})
[1] "show"
> show(foo)
show method
> foo
show method
> print(foo)
show method
> # suppressed because output depends on current choice of S4 type or
> # not.  Can reinstate when S4 type is obligatory
> # print(foo, digits = 4)
> 
> ## DON'T DO THIS:  S3 methods for S4 classes are a design error JMC iii.9.09
> ## print.bar <- function(x, ...) cat("print method\n")
> ## foo
> ## print(foo)
> ## show(foo)
> 
> setMethod("print", "bar", function(x, ...){cat("S4 print method\n")})
Creating a generic function for 'print' from package 'base' in the global environment
[1] "print"
> foo
show method
> print(foo)
S4 print method
> show(foo)
show method
> ## calling print() with more than one argument suppresses the show()
> ## method, largely to prevent an infinite loop if there is in fact no
> ## show() method for this class.  A better solution would be desirable.
> print(foo, digits = 4)
S4 print method
> 
> setClassUnion("integer or NULL", members = c("integer","NULL"))
[1] "integer or NULL"
> setClass("c1", representation(x = "integer", code = "integer or NULL"))
[1] "c1"
> nc <- new("c1", x = 1:2)
> str(nc)# gave ^ANULL^A in 2.0.0
Formal class 'c1' [package ".GlobalEnv"] with 2 slots
  ..@ x   : int [1:2] 1 2
  ..@ code: NULL
> ##
> 
> 
> library(stats4)
> showMethods("coerce", classes=c("matrix", "numeric"))
Function: coerce (package methods)
from="ANY", to="matrix"
from="ANY", to="numeric"

> ## {gave wrong result for a while in R 2.4.0}
> 
> ## the following showMethods() output tends to generate errors in the tests
> ## whenever the contents of the packages change. Searching in the
> ## diff's can easily mask real problems.  If there is a point
> ## to the printout, e.g., to verify that certain methods exist,
> ## hasMethod() would be a useful replacement
> 
> ## showMethods(where = "package:stats4")
> ## showMethods("show")
> ## showMethods("show")
> ## showMethods("plot") # (ANY,ANY) and (profile.mle, missing)
> ## showMethods(classes="mle")
> ## showMethods(classes="matrix")
> 
> 
> ##--- "[" fiasco before R 2.2.0 :
> d2 <- data.frame(b= I(matrix(1:6,3,2)))
> ## all is well:
> d2[2,]
     [,1] [,2]
[1,]    2    5
> stopifnot(identical(d2[-1,], d2[2:3,]))
> ## Now make "[" into S4 generic by defining a trivial method
> setClass("Mat", representation(Dim = "integer", "VIRTUAL"))
[1] "Mat"
> setMethod("[", signature(x = "Mat",
+            i = "missing", j = "missing", drop = "ANY"),
+     function (x, i, j, drop) x)
[1] "["
> ## Can even remove the method: it doesn't help
> removeMethod("[", signature(x = "Mat",
+                             i = "missing", j = "missing", drop = "ANY"))
[1] TRUE
> d2[1:2,] ## used to fail badly; now okay
     [,1] [,2]
[1,]    1    4
[2,]    2    5
> stopifnot(identical(d2[-1,], d2[2:3,]))
> ## failed in R <= 2.1.x
> 
> 
> ## Fritz' S4 "odditiy"
> setClass("X", representation(bar="numeric"))
[1] "X"
> setClass("Y", contains="X")
[1] "Y"
> ## Now we define a generic foo() and two different methods for "X" and
> ## "Y" objects for arg missing:
> setGeneric("foo", function(object, arg) standardGeneric("foo"))
[1] "foo"
> setMethod("foo", signature(object= "X", arg="missing"),
+           function(object, arg) cat("an X object with bar =", object@bar, "\n"))
[1] "foo"
> setMethod("foo", signature(object= "Y", arg="missing"),
+           function(object, arg) cat("a Y object with bar =", object@bar, "\n"))
[1] "foo"
> ## Finally we create a method where arg is "logical" only for class
> ## "X", hence class "Y" should inherit that:
> setMethod("foo", signature(object= "X", arg= "logical"),
+           function(object, arg) cat("Hello World!\n") )
[1] "foo"
> ## now create objects and call methods:
> y <- new("Y", bar=2)
> ## showMethods("foo")
> foo(y)
a Y object with bar = 2 
> foo(y, arg=TRUE)## Hello World!
Hello World!
> ## OK, inheritance worked, and we have
> ## showMethods("foo")
> foo(y)
a Y object with bar = 2 
> ## still 'Y' -- was 'X object' in R < 2.3
> 
> 
> ## Multiple inheritance
> setClass("A", representation(x = "numeric"))
[1] "A"
> setClass("B", representation(y = "character"))
[1] "B"
> setClass("C", contains = c("A", "B"), representation(z = "logical"))
[1] "C"
> new("C")
An object of class "C"
Slot "z":
logical(0)

Slot "x":
numeric(0)

Slot "y":
character(0)

> setClass("C", contains = c("A", "B"), representation(z = "logical"),
+          prototype = prototype(x = 1.5, y = "test", z = TRUE))
[1] "C"
> (cc <- new("C"))
An object of class "C"
Slot "z":
[1] TRUE

Slot "x":
[1] 1.5

Slot "y":
[1] "test"

> ## failed reconcilePropertiesAndPrototype(..) after svn r37018
> stopifnot(identical(selectSuperClasses("C", dropVirtual = TRUE), c("A", "B")),
+     0 == length(.selectSuperClasses(getClass("B")@contains)))
> 
> ## "Logic" group -- was missing in R <= 2.4.0
> stopifnot(all(getGroupMembers("Logic") %in% c("&", "|")),
+     any(getGroupMembers("Ops") == "Logic"))
> setClass("brob", contains="numeric")
[1] "brob"
> b <- new("brob", 3.14)
> logic.brob.error <- function(nm)
+     stop("logic operator '", nm, "' not applicable to brobs")
> logic2 <- function(e1,e2) logic.brob.error(.Generic)
> setMethod("Logic", signature("brob", "ANY"), logic2)
[1] "Logic"
> setMethod("Logic", signature("ANY", "brob"), logic2)
[1] "Logic"
> ## Now ensure that using group members gives error:
> assertError <- function(expr)
+     stopifnot(inherits(try(expr, silent = TRUE), "try-error"))
> assertWarning <- function(expr)
+     stopifnot(inherits(tryCatch(expr, warning = function(w)w), "warning"))
> assertWarning_atleast <- function(expr) {
+     r <- tryCatch(expr, warning = function(w)w, error = function(e)e)
+     stopifnot(inherits(r, "warning") || inherits(r, "error"))
+ }
> 
> assertError(b & b)
Note: Method with signature "brob#ANY" chosen for function "&",
 target signature "brob#brob".
 "ANY#brob" would also be valid
> assertError(b | 1)
> assertError(TRUE & b)
> 
> 
> ## methods' hidden cbind() / rbind:
> cBind <- methods:::cbind
> setClass("myMat", representation(x = "numeric"))
[1] "myMat"
> setMethod("cbind2", signature(x = "myMat", y = "missing"), function(x,y) x)
[1] "cbind2"
> m <- new("myMat", x = c(1, pi))
> stopifnot(identical(m, cBind(m)))
> 
> 
> ## explicit print or show on a basic class with an S4 bit
> ## caused infinite recursion
> setClass("Foo", representation(name="character"), contains="matrix")
[1] "Foo"
> (f <- new("Foo", name="Sam", matrix()))
An object of class "Foo"
     [,1]
[1,]   NA
Slot "name":
[1] "Sam"

> f2 <- new("Foo", .Data = diag(2), name="Diag")# explicit .Data
> (m <- as(f, "matrix"))
     [,1]
[1,]   NA
> ## this has no longer (2.7.0) an S4 bit: set it explicitly just for testing:
> stopifnot(isS4(m. <- asS4(m)),
+           identical(m, f@.Data),
+     .hasSlot(f, "name"))# failed in R <= 2.13.1
> show(m.)
     [,1]
[1,]   NA
> print(m.)
     [,1]
[1,]   NA
> ## fixed in 2.5.0 patched
> 
> ## callGeneric inside a method with new arguments {hence using .local()}:
> setGeneric("Gfun", function(x, ...) standardGeneric("Gfun"),
+      useAsDefault = function(x, ...) sum(x, ...))
[1] "Gfun"
> setClass("myMat", contains="matrix")
[1] "myMat"
> setClass("mmat2", contains="matrix")
[1] "mmat2"
> setClass("mmat3", contains="mmat2")
[1] "mmat3"
> setMethod(Gfun, signature(x = "myMat"),
+     function(x, extrarg = TRUE) {
+         cat("in 'myMat' method for 'Gfun() : extrarg=", extrarg, "\n")
+         Gfun(unclass(x))
+     })
[1] "Gfun"
attr(,"package")
[1] ".GlobalEnv"
> setMethod(Gfun, signature(x = "mmat2"),
+     function(x, extrarg = TRUE) {
+         cat("in 'mmat2' method for 'Gfun() : extrarg=", extrarg, "\n")
+         x <- unclass(x)
+         callGeneric()
+     })
[1] "Gfun"
attr(,"package")
[1] ".GlobalEnv"
> setMethod(Gfun, signature(x = "mmat3"),
+     function(x, extrarg = TRUE) {
+         cat("in 'mmat3' method for 'Gfun() : extrarg=", extrarg, "\n")
+         x <- as(x, "mmat2")
+         callGeneric()
+     })
[1] "Gfun"
attr(,"package")
[1] ".GlobalEnv"
> wrapG <- function(x, a1, a2) {
+     myextra <- missing(a1) && missing(a2)
+     Gfun(x, extrarg = myextra)
+ }
> 
> (mm <- new("myMat", diag(3)))
An object of class "myMat"
     [,1] [,2] [,3]
[1,]    1    0    0
[2,]    0    1    0
[3,]    0    0    1
> Gfun(mm)
in 'myMat' method for 'Gfun() : extrarg= TRUE 
[1] 3
> stopifnot(identical(wrapG(mm),    Gfun(mm, TRUE)),
+           identical(wrapG(mm,,2), Gfun(mm, FALSE)))
in 'myMat' method for 'Gfun() : extrarg= TRUE 
in 'myMat' method for 'Gfun() : extrarg= TRUE 
in 'myMat' method for 'Gfun() : extrarg= FALSE 
in 'myMat' method for 'Gfun() : extrarg= FALSE 
> 
> Gfun(mm, extrarg = FALSE)
in 'myMat' method for 'Gfun() : extrarg= FALSE 
[1] 3
> m2 <- new("mmat2", diag(3))
> Gfun(m2)
in 'mmat2' method for 'Gfun() : extrarg= TRUE 
[1] 3
> Gfun(m2, extrarg = FALSE)
in 'mmat2' method for 'Gfun() : extrarg= FALSE 
[1] 3
> ## The last two gave Error ...... variable ".local" was not found
> (m3 <- new("mmat3", diag(3)))
An object of class "mmat3"
     [,1] [,2] [,3]
[1,]    1    0    0
[2,]    0    1    0
[3,]    0    0    1
> Gfun(m3)
in 'mmat3' method for 'Gfun() : extrarg= TRUE 
in 'mmat2' method for 'Gfun() : extrarg= TRUE 
[1] 3
> Gfun(m3, extrarg = FALSE) # used to not pass 'extrarg'
in 'mmat3' method for 'Gfun() : extrarg= FALSE 
in 'mmat2' method for 'Gfun() : extrarg= FALSE 
[1] 3
> 
> ## -- a variant of the above which failed in version <= 2.5.1 :
> setGeneric("Gf", function(x, ...) standardGeneric("Gf"))
[1] "Gf"
> setMethod(Gf, signature(x = "mmat2"),
+           function(x, ...) {
+               cat("in 'mmat2' method for 'Gf()\n")
+               x <- unclass(x)
+               callGeneric()
+           })
[1] "Gf"
attr(,"package")
[1] ".GlobalEnv"
> setMethod(Gf, signature(x = "mmat3"),
+           function(x, ...) {
+               cat("in 'mmat3' method for 'Gf()\n")
+               x <- as(x, "mmat2")
+               callGeneric()
+           })
[1] "Gf"
attr(,"package")
[1] ".GlobalEnv"
> setMethod(Gf, signature(x = "matrix"),
+     function(x, a1, ...) {
+               cat(sprintf("matrix %d x %d ...\n", nrow(x), ncol(x)))
+               list(x=x, a1=a1, ...)
+           })
[1] "Gf"
attr(,"package")
[1] ".GlobalEnv"
> 
> wrap2 <- function(x, a1, ...) {
+     A1 <- if(missing(a1)) "A1" else as.character(a1)
+     Gf(x, ..., a1 = A1)
+ }
> ## Gave errors in R 2.5.1 :
> wrap2(m2, foo = 3.14)
in 'mmat2' method for 'Gf()
matrix 3 x 3 ...
$x
     [,1] [,2] [,3]
[1,]    1    0    0
[2,]    0    1    0
[3,]    0    0    1

$a1
[1] "A1"

$foo
[1] 3.14

> wrap2(m2, 10, answer.all = 42)
in 'mmat2' method for 'Gf()
matrix 3 x 3 ...
$x
     [,1] [,2] [,3]
[1,]    1    0    0
[2,]    0    1    0
[3,]    0    0    1

$a1
[1] "10"

$answer.all
[1] 42

> 
> 
> ## regression tests of dispatch: most of these became primitive in 2.6.0
> setClass("c1", "numeric")
[1] "c1"
> setClass("c2", "numeric")
[1] "c2"
> x_c1 <- new("c1")
> # the next failed < 2.5.0 as the signature in .BasicFunsList was wrong
> setMethod("as.character", "c1", function(x, ...) "fn test")
[1] "as.character"
> as.character(x_c1)
[1] "fn test"
> 
> setMethod("as.integer", "c1", function(x, ...) 42)
[1] "as.integer"
> as.integer(x_c1)
[1] 42
> 
> setMethod("as.logical", "c1", function(x, ...) NA)
[1] "as.logical"
> as.logical(x_c1)
[1] NA
> 
> setMethod("as.complex", "c1", function(x, ...) pi+0i)
[1] "as.complex"
> as.complex(x_c1)
[1] 3.141593+0i
> 
> setMethod("as.raw", "c1", function(x) as.raw(10))
[1] "as.raw"
> as.raw(x_c1)
[1] 0a
> 
> # as.double, as.real use as.numeric for their methods to maintain equivalence
> setMethod("as.numeric", "c1", function(x, ...) 42+pi)
[1] "as.numeric"
> identical(as.numeric(x_c1),as.double(x_c1))
[1] TRUE
> identical(as.numeric(x_c1),as.real(x_c1))
[1] TRUE
> 
> 
> setMethod(as.double, "c2", function(x, ...) x@.Data+pi)
[1] "as.numeric"
> x_c2 <- new("c2", pi)
> identical(as.numeric(x_c2),as.double(x_c2))
[1] TRUE
> identical(as.numeric(x_c2),as.real(x_c2))
[1] TRUE
> 
> ## '!' changed signature from 'e1' to 'x' in 2.6.0
> setClass("foo", "logical")
[1] "foo"
> setMethod("!", "foo", function(e1) e1+NA)
[1] "!"
Warning message:
For function '!', signature "foo": argument in method definition changed from (e1) to (x) 
> selectMethod("!", "foo")
Method Definition:

function (x) 
x + NA

Signatures:
        x    
target  "foo"
defined "foo"
> xx <- new("foo", FALSE)
> !xx
An object of class "foo"
[1] NA
> 
> ## This failed for about one day -- as.vector(x, mode) :
> setMethod("as.vector", signature(x = "foo", mode = "missing"),
+           function(x) unclass(x))
Creating a generic function for 'as.vector' from package 'base' in the global environment
[1] "as.vector"
> ## whereas this fails in R versions earlier than 2.6.0:
> setMethod("as.vector", "foo", function(x) unclass(x))
[1] "as.vector"
> stopifnot(removeClass("foo"))
> 
> ## stats4::AIC in R < 2.7.0 used to clobber stats::AIC
> pfit <- function(data) {
+     m <- mean(data)
+     loglik <- sum(dpois(data, m))
+     ans <- list(par = m, loglik = loglik)
+     class(ans) <- "pfit"
+     ans
+ }
> AIC.pfit <- function(object, ..., k = 2) -2*object$loglik + k
> AIC(pfit(1:10))
[1] 0.05867604
> library(stats4) # and keep on search() for tests below
> AIC(pfit(1:10)) # failed in R < 2.7.0
[1] 0.05867604
> 
> ## For a few days (~ 2008-01-30), this failed to work without any notice:
> setClass("Mat",  representation(Dim = "integer","VIRTUAL"))
[1] "Mat"
> setClass("dMat", representation(x = "numeric",  "VIRTUAL"), contains = "Mat")
[1] "dMat"
> setClass("CMat", representation(dnames = "list","VIRTUAL"), contains = "Mat")
[1] "CMat"
> setClass("dCMat", contains = c("dMat", "CMat"))
[1] "dCMat"
> stopifnot(!isVirtualClass("dCMat"),
+     length(slotNames(new("dCMat"))) == 3)
> 
> 
> ## Passing "..." arguments in nested callGeneric()s
> setClass("m1", contains="matrix")
[1] "m1"
> setClass("m2", contains="m1")
[1] "m2"
> setClass("m3", contains="m2")
[1] "m3"
> ##
> setGeneric("foo", function(x, ...) standardGeneric("foo"))
[1] "foo"
> setMethod("foo", signature(x = "m1"),
+     function(x, ...) cat(" <m1> ", format(match.call()),"\n"))
[1] "foo"
> setMethod("foo", signature(x = "m2"),
+     function(x, ...) {
+         cat(" <m2> ", format(match.call()),"\n")
+         x <- as(x, "m1"); callGeneric()
+     })
[1] "foo"
> setMethod("foo", signature(x = "m3"),
+     function(x, ...) {
+         cat(" <m3> ", format(match.call()),"\n")
+         x <- as(x, "m2"); callGeneric()
+     })
[1] "foo"
> foo(new("m1"), bla = TRUE)
 <m1>  foo(x = new("m1"), bla = TRUE) 
> foo(new("m2"), bla = TRUE)
 <m2>  foo(x = new("m2"), bla = TRUE) 
 <m1>  foo(x = x, bla = TRUE) 
> foo(new("m3"), bla = TRUE)
 <m3>  foo(x = new("m3"), bla = TRUE) 
 <m2>  foo(x = x, bla = TRUE) 
 <m1>  foo(x = x, bla = TRUE) 
> ## The last one used to loose 'bla = TRUE' {the "..."} when it got to m1
> 
> ## is() for S3 objects with multiple class strings
> setClassUnion("OptionalPOSIXct",   c("POSIXct",   "NULL"))
[1] "OptionalPOSIXct"
> stopifnot(is(Sys.time(), "OptionalPOSIXct"))
> ## failed in R 2.7.0
> 
> ## getGeneric() / getGenerics() "problems" related to 'tools' usage:
> e4 <- as.environment("package:stats4")
> gg4 <- getGenerics(e4)
> stopifnot(c("BIC", "coef", "confint", "logLik", "plot", "profile",
+             "show", "summary", "update", "vcov") %in% gg4, # %in% : "future proof"
+           unlist(lapply(gg4, function(g) !is.null(getGeneric(g, where = e4)))),
+           unlist(lapply(gg4, function(g) !is.null(getGeneric(g)))))
> em <- as.environment("package:methods")
> ggm <- getGenerics(em)
> gms <- c("addNextMethod", "body<-", "cbind2", "initialize",
+    "loadMethod", "Ops", "rbind2", "show")
> stopifnot(unlist(lapply(ggm, function(g) !is.null(getGeneric(g, where = em)))),
+     unlist(lapply(ggm, function(g) !is.null(getGeneric(g)))),
+     gms %in% ggm,
+     gms %in% tools:::get_S4_generics_with_methods(em), # with "message"
+     ## all above worked in 2.7.0, however:
+     isGeneric("show",  where=e4),
+     hasMethods("show", where=e4), hasMethods("show", where=em),
+     ## isGeneric("dim", where=as.environment("package:Matrix"))
+     identical(as.character(gg4), #gg4 has packages attr.; tools::: doesn't
+           tools:::get_S4_generics_with_methods(e4))
+     )
> ## the last failed in R 2.7.0 : was not showing  "show"
> ## TODO: use "Matrix" checks once that is >= 1.0
> 
> ## containing "array" ("matrix", "ts", ..)
> t. <- ts(1:10, frequency = 4, start = c(1959, 2))
> setClass("Arr", contains= "array"); x <- new("Arr", cbind(17))
[1] "Arr"
> setClass("Ts",  contains= "ts");   tt <- new("Ts", t.); t2 <- as(t., "Ts")
[1] "Ts"
> setClass("ts2", representation(x = "Ts", y = "ts"))
[1] "ts2"
> tt2 <- new("ts2", x=t2, y=t.)
> stopifnot(dim(x) == c(1,1), is(tt, "ts"), is(t2, "ts"),
+           ## FIXME:  identical(tt, t2)
+           length(tt) == length(t.),
+           identical(tt2@x, t2), identical(tt2@y, t.))
> ## new(..) failed in R 2.7.0
> 
> ## Method with wrong argument order :
> setGeneric("test1", function(x, printit = TRUE, name = "tmp")
+            standardGeneric("test1"))
[1] "test1"
> assertWarning_atleast(
+ setMethod("test1", "numeric", function(x, name, printit) match.call())
+ )## did not warn or error in R 2.7.0 and earlier
> 
> library(stats4)
> c1 <- getClass("mle", where = "stats4")
> c2 <- getClass("mle", where = "package:stats4")
> s1 <- getMethod("summary", "mle", where = "stats4")
> s2 <- getMethod("summary", "mle", where = "package:stats4")
> stopifnot(is(c1, "classRepresentation"),
+     is(s1, "MethodDefinition"),
+     identical(c1,c2), identical(s1,s2))
> ## failed at times in the past
> 
> ## Extending "matrix", the .Data slot etc:
> setClass("moo", representation("matrix"))
[1] "moo"
> m <- matrix(1:4, 2, dimnames= list(NULL, c("A","B")))
> nf <- new("moo", .Data = m)
> n2 <- new("moo", 3:1, 3,2)
> n3 <- new("moo", 1:6, ncol=2)
> stopifnot(identical(m,            as(nf, "matrix")),
+     identical(matrix(3:1,3,2),    as(n2, "matrix")),
+     identical(matrix(1:6,ncol=2), as(n3, "matrix")))
> ## partly failed at times in pre-2.8.0
> 
> ## From "Michael Lawrence" <....@fhcrc.org>  To r-devel@r-project, 25 Nov 2008:
> ## NB: setting a generic on order() is *not* the approved method
> ## -- set xtfrm() methods instead
> setGeneric("order", signature="...",
+      function (..., na.last=TRUE, decreasing=FALSE)
+      standardGeneric("order"))
Creating a new generic function for 'order' in the global environment
[1] "order"
> stopifnot(identical(rbind(1), matrix(1,1,1)))
> setGeneric("rbind", function(..., deparse.level=1)
+      standardGeneric("rbind"), signature = "...")
Creating a new generic function for 'rbind' in the global environment
[1] "rbind"
> stopifnot(identical(rbind(1), matrix(1,1,1)))
> ## gave Error in .Method( .... in R 2.8.0
> 
> ## median( <simple S4> )
> ## FIXME: if we use "C" instead of "L", this fails because of caching
> setClass("L", contains = "list")
[1] "L"
> ## {simplistic, just for the sake of testing here} :
> setMethod("Compare", signature(e1="L", e2="ANY"),
+           function(e1,e2) sapply(e1, .Generic, e2=e2))
[1] "Compare"
> ## note the next does *not* return an object of the class.
> setMethod("Summary", "L",
+     function(x, ..., na.rm=FALSE) {x <- unlist(x); callNextMethod()})
[1] "Summary"
> setMethod("[", signature(x="L", i="ANY", j="missing",drop="missing"),
+           function(x,i,j,drop) new(class(x), x@.Data[i]))
[1] "["
> ## defining S4 methods for sort() has no effect on calls to
> ## sort() from functions in a namespace; e.g., median.default.
> ## but setting an xtfrm() method works.
> setMethod("xtfrm", "L", function(x) xtfrm(unlist(x@.Data)))
[1] "xtfrm"
> ## median is documented to use mean(), so we need an S3 mean method:
> ## An S4 method will not do because of the long-standing S4 scoping bug.
> mean.L <- function(x, ...) new("L", mean(unlist(x@.Data), ...))
> x <- new("L", 1:3); x2 <- x[-2]
> stopifnot(unlist(x2) == (1:3)[-2],
+     is(mx <- median(x), "L"), mx == 2,
+     ## median of two
+     median(x2) == x[2])
> ## NB: quantile() is not said to work on such an object, and only does so
> ## for order statistics (so should not be tested, but was in earlier versions).
> 
> ## Buglet in as() generation for class without own slots
> setClass("SIG", contains="signature")
[1] "SIG"
> stopifnot(packageSlot(class(S <- new("SIG"))) == ".GlobalEnv",
+     packageSlot(class(ss <- new("signature"))) == "methods",
+     packageSlot(class(as(S, "signature"))) == "methods")
> ## the 3rd did not have "methods"
> 
> ## Invalid "factor"s -- now "caught" by  validity check :
>  ok.f <- gl(3,5, labels = letters[1:3])
> bad.f <- structure(rep(1:3, each=5), levels=c("a","a","b"), class="factor")
> validObject(ok.f) ; assertError(validObject(bad.f))
[1] TRUE
> setClass("myF", contains = "factor")
[1] "myF"
> validObject(new("myF", ok.f))
[1] TRUE
> assertError(validObject(new("myF", bad.f)))
> removeClass("myF")
[1] TRUE
> ## no validity check in R <= 2.9.0
> 
> ## as(x, .)   when x is from an "unregistered" S3 class :
> as(structure(1:3, class = "foobar"), "vector")
[1] 1 2 3
> ## failed to work in R <= 2.9.0
> 
> ## S4 dispatch in the internal generic xtfrm (added in 2.11.0)
> setClass("numWithId", representation(id = "character"), contains = "numeric")
[1] "numWithId"
> x <- new("numWithId", 1:3, id = "An Example")
> xtfrm(x) # works as the base representation is numeric
[1] 1 2 3
attr(,"id")
[1] "An Example"
> setMethod('xtfrm', 'numWithId', function(x) x@.Data)
[1] "xtfrm"
> xtfrm(x)
[1] 1 2 3
> stopifnot(identical(xtfrm(x), 1:3))
> ## new in 2.11.0
> 
> ## [-dispatch using callNextMethod()
> setClass("C1", representation(a = "numeric"))
[1] "C1"
> setClass("C2", contains = "C1")
[1] "C2"
> setMethod("[", "C1", function(x,i,j,...,drop=TRUE)
+     cat("drop in C1-[ :", drop, "\n"))
[1] "["
> setMethod("[", "C2", function(x,i,j,...,drop=TRUE) {
+     cat("drop in C2-[ :", drop, "\n")
+     callNextMethod()
+ })
[1] "["
> x <- new("C1"); y <- new("C2")
> x[1, drop=FALSE]
drop in C1-[ : FALSE 
NULL
> y[1, drop=FALSE]
drop in C2-[ : FALSE 
drop in C1-[ : FALSE 
NULL
> ## the last gave TRUE on C1-level in R 2.10.x;
> ## the value of drop was wrongly taken from the default.
> 
> ## All slot names -- but "class" -- should work now
> problNames <- c("names", "dimnames", "row.names",
+                 "class", "comment", "dim", "tsp")
> myTry <- function(expr, ...) tryCatch(expr, error = function(e) e)
> tstSlotname <- function(nm) {
+     r <- myTry(setClass("foo", representation =
+                         structure(list("character"), .Names = nm)))
+     if(is(r, "error")) return(r$message)
+     ## else
+     ch <- LETTERS[1:5]
+     ## instead of  new("foo", <...> = ch):
+     x <- myTry(do.call(new, structure(list("foo", ch), .Names=c("", nm))))
+     if(is(x, "error")) return(x$message)
+     y <- myTry(new("foo"));        if(is(y, "error")) return(y$message)
+     r <- myTry(capture.output(show(x))); if(is(r, "error")) return(r$message)
+     r <- myTry(capture.output(show(y))); if(is(r, "error")) return(r$message)
+     ## else
+     slot(y, nm) <- slot(x, nm)
+     stopifnot(validObject(x), identical(x,y), identical(slot(x, nm), ch))
+     return(TRUE)
+ }
> R <- sapply(problNames, tstSlotname, simplify = FALSE)
> str(R) # just so ...
List of 7
 $ names    : logi TRUE
 $ dimnames : logi TRUE
 $ row.names: logi TRUE
 $ class    : chr "\"class\" is a reserved slot name and cannot be redefined"
 $ comment  : logi TRUE
 $ dim      : logi TRUE
 $ tsp      : logi TRUE
> stopifnot(is.character(R[["class"]]),
+           sapply(R[names(R) != "class"], isTRUE))
> ## only "class" (and ".Data", ...) is reserved as slot name
> 
> ## implicit generics ..
> setMethod("sample", "C2",
+           function(x, size, replace=FALSE, prob=NULL) {"sample.C2"})
Creating a generic function for 'sample' from package 'base' in the global environment
[1] "sample"
> stopifnot(is(sample,"standardGeneric"),
+     ## the signature must come from the implicit generic:
+     identical(sample@signature, c("x", "size")),
+     identical(packageSlot(sample), "base"),
+     ## default method must still work:
+     identical({set.seed(3); sample(3)}, 1:3))
> ## failed in R 2.11.0
> 
> ## Still, signature is taken from "def"inition, if one is provided:
> ## (For test, qqplot must be a "simple" function:)
> stopifnot(is.function(qqplot) && identical(class(qqplot), "function"))
> setGeneric("qqplot", function(x, y, ...) standardGeneric("qqplot"))
Creating a new generic function for 'qqplot' in the global environment
[1] "qqplot"
> stopifnot(is(qqplot, "standardGeneric"),
+     identical(qqplot@signature, c("x","y")))
> ## failed for a day ~ 2005-05-26, for R-devel only
> 
> 
> ##  'L$A@x <- ..'
> setClass("foo", representation(x = "numeric"))
[1] "foo"
> f <- new("foo", x = pi*1:2)
> L <- list()
> L$A <- f
> L$A@x[] <- 7
> if( identical(f, L$A) )
+     stop("Oops! f is identical to L$A, even though not touched!")
> ## did not duplicate in 2.0.0 <= Rversion <= 2.11.1
> 
>