showMethods {methods} | R Documentation

## Show all the methods for the specified function(s)

### Description

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

### Usage

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

### Arguments

`f` | one or more function names. If omitted, all functions will be examined.
`where` | If `where` is supplied, the methods definition from that position will be used; otherwise, the current definition is used (which will include inherited methods that have arisen so far in the session). If `f` is omitted, `where` controls where to look for generic functions.
`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 if methods with empty method lists should be shown at all. Note that `FALSE` is not yet implemented.
`printTo` | The connection on which the printed information will be written. 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`.

### Details

The output style is different from S-Plus in that it does not show the database from which the definition comes, but can optionally include the method definitions.

### Value

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

### References

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. For a discussion of details and ongoing development, see the web page http://developer.r-project.org/methodsPackage.html and the pointers from that page.

### 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.

### Examples

    ## 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)

    ## Show all methods from the same place that a class is defined:
    not.there <- !any("package:stats4" == search())
    if(not.there) library(stats4)
    showMethods(class = "mle")                           # not really helpful
    showMethods(class = "mle", where = "package:stats4") # much better
    if(not.there) detach("package:stats4")

[Package methods version 2.3.1 Index]