showMethods {methods}R Documentation

Show all the methods for the specified function(s)


Show a summary of the methods for one or more generic functions, possibly restricted to those involving specified classes.


showMethods(f = character(), where = topenv(parent.frame()),
            classes = NULL, includeDefs = FALSE, inherited = TRUE,
            showEmpty, printTo = stdout())


f one or more function names. If omitted, all functions will be shown that match the other arguments.
where Used only when f is missing, or length 0, to determine which generic functions to examine. If where is supplied, only the generic functions returned by getGenerics(where) are eligible for printing. If where is also missing, all the cached generic functions are considered.
classes If argument classes is supplied, it is a vector of class names that restricts the displayed results to those methods whose signatures include one or more of those classes.
includeDefs If includeDefs is TRUE, include the definitions of the individual methods in the printout.
inherited If inherits is TRUE, then methods that have been found by inheritance, so far in the session, will be included and marked as inherited. Note that an inherited method will not usually appear until it has been used in this session. See selectMethod if you want to know what method is dispatched for particular classes of arguments.
showEmpty logical indicating whether methods with no defined methods matching the other criteria should be shown at all. By default, TRUE if and only if argument f is not missing.
printTo The connection on which the printed information will be written; by default, standard output. If printTo is FALSE, the output will be collected as a character vector and returned as the value of the call to showMethod. See show.


The name and package of the generic are followed by the list of signatures for which methods are currently defined, according to the criteria determined by the various arguments. Note that the package refers to the source of the generic function. Individual methods for that generic can come from other packages as well.


If printTo is FALSE, the character vector that would have been printed is returned; otherwise the value is the connection or filename, via invisible.


The R package methods implements, with a few exceptions, the programming interface for classes and methods in the book Programming with Data (John M. Chambers, Springer, 1998), in particular sections 1.6, 2.7, 2.8, and chapters 7 and 8.

While the programming interface for the methods package follows the reference, the R software is an original implementation, so details in the reference that reflect the S4 implementation may appear differently in R. Also, there are extensions to the programming interface developed more recently than the reference. See Methods and references from there.

See Also

setMethod, and GenericFunctions for other tools involving methods; selectMethod will show you the method dispatched for a particular function and signature of classes for the arguments.


## Assuming the methods for plot
## are set up as in the example of help(setMethod),
## print (without definitions) the methods that involve class "track":
showMethods("plot", classes = "track")
## Not run: 
Function "plot":
x = ANY, y = track
x = track, y = missing
x = track, y = ANY
## End(Not run)

not.there <- !any("package:stats4" == search())
if(not.there) library(stats4)
showMethods(class = "mle")
if(not.there) detach("package:stats4")

[Package methods version 2.5.0 Index]