| showMethods {methods} | R Documentation |
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 = TRUE, printTo = stdout())
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.
|
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.
If printTo is FALSE, the character vector that would
have been printed is returned; otherwise the value is the connection
or filename.
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.
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)
## 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")