Creates an S3 method

Creates an S3 method. A function with name <name>.<class> will be set to definition. The method will get the modifiers specified by modifiers. If there exists no generic function for this method, it will be created automatically.

# Default S3 method
setMethodS3(name, class="default", definition, private=FALSE, protected=FALSE,
  export=FALSE, static=FALSE, abstract=FALSE, trial=FALSE, deprecated=FALSE,
  envir=parent.frame(), overwrite=TRUE, conflict=c("warning", "error", "quiet"),
  createGeneric=TRUE, exportGeneric=TRUE, appendVarArgs=TRUE,
  validators=getOption("R.methodsS3:validators:setMethodS3"), ...)

Arguments

name: The name of the method.
class: The class for which the method should be defined. If class == "default" a function with name <name>.default will be created.
definition: The method definition.
private, protected: If private=TRUE, the method is declared private. If protected=TRUE, the method is declared protected. In all other cases the method is declared public.
export: A logical setting attribute "export".
static: If TRUE this method is defined to be static, otherwise not. Currently this has no effect expect as an indicator.
abstract: If TRUE this method is defined to be abstract, otherwise not. Currently this has no effect expect as an indicator.
trial: If TRUE this method is defined to be a trial method, otherwise not. A trial method is a method that is introduced to be tried out and it might be modified, replaced or even removed in a future release. Some people prefer to call trial versions, beta version. Currently this has no effect expect as an indicator.
deprecated: If TRUE this method is defined to be deprecated, otherwise not. Currently this has no effect expect as an indicator.
envir: The environment for where this method should be stored.
overwrite: If TRUE an already existing generic function and an already existing method with the same name (and of the same class) will be overwritten, otherwise not.
conflict: If a method already exists with the same name (and of the same class), different actions can be taken. If "error", an exception will be thrown and the method will not be created. If "warning", a warning will be given and the method will be created, otherwise the conflict will be passed unnoticed.
createGeneric, exportGeneric: If createGeneric=TRUE, a generic S3/UseMethod function is defined for this method, iff missing, and exportGeneric species attribute "export" of it.
appendVarArgs: If TRUE, argument ... is added with a warning, if missing. For special methods such as $ and [[, this is never done (argument is ignored). This will increase the chances that the method is consistent with a generic function with many arguments and/or argument ....
validators: An optional list of functions that can be used to assert that the generated method meets certain criteria.
...: Passed to setGenericS3(), iff called.

Author

Henrik Bengtsson

Examples

######################################################################
# Example 1
######################################################################
setMethodS3("foo", "default", function(x, ...) {
  cat("In default foo():\n");
  print(x, ...);
})


setMethodS3("foo", "character", function(s, ...) {
  cat("In foo() for class 'character':\n");
  print(s, ...);
})
#> NULL

# The generic function is automatically created!
print(foo)
#> function (...) 
#> UseMethod("foo")
#> <environment: 0x569a8f745fe0>
#> attr(,"export")
#> [1] TRUE

foo(123)
#> In default foo():
#> [1] 123
foo("123")
#> In foo() for class 'character':
#> [1] "123"


######################################################################
# Example 2
#
# Assume that in a loaded package there is already a function bar(),
# but you also want to use the name 'bar' for the character string.
# It may even be the case that you do not know of the other package,
# but your users do!
######################################################################
# bar() in other package
bar <- function(x, y, ...) {
  cat("In bar() of 'other' package.\n");
}


# Your definition; will redefine bar() above to bar.default().
setMethodS3("bar", "character", function(object, ...) {
  cat("In bar() for class 'character':\n");
  print(object, ...);
})
#> Warning: Renamed the preexisting function bar to bar.default, which was defined in environment .

bar(123)
#> In bar() of 'other' package.
bar("123")
#> In bar() for class 'character':
#> [1] "123"

Arguments

See also

Author

Examples