| % File src/library/methods/man/show.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2016 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{show} |
| \alias{show} |
| \alias{show-methods} |
| \alias{show,ANY-method} |
| \alias{show,traceable-method} |
| \alias{show,ObjectsWithPackage-method} |
| \alias{show,MethodDefinition-method} |
| \alias{show,MethodWithNext-method} |
| \alias{show,genericFunction-method} |
| \alias{show,classRepresentation-method} |
| \title{Show an Object} |
| \description{ |
| Display the object, by printing, plotting or whatever suits its |
| class. This function exists to be specialized by methods. The |
| default method calls \code{\link{showDefault}}. |
| |
| Formal methods for \code{show} will |
| usually be invoked for automatic printing (see the details). |
| } |
| \usage{ |
| show(object) |
| } |
| \arguments{ |
| \item{object}{Any R object} |
| } |
| \value{ |
| \code{show} returns an invisible \code{NULL}. |
| } |
| \details{ |
| Objects from an S4 class (a class defined by a call to |
| \code{\link{setClass}}) will be displayed automatically is if by a |
| call to \code{show}. S4 objects that occur as attributes of S3 |
| objects will also be displayed in this form; conversely, S3 objects |
| encountered as slots in S4 objects will be printed using the S3 |
| convention, as if by a call to \code{\link{print}}. |
| |
| Methods defined for \code{show} will only be inherited by simple |
| inheritance, since otherwise the method would not receive the |
| complete, original object, with misleading results. See the |
| \code{simpleInheritanceOnly} argument to \code{\link{setGeneric}} and |
| the discussion in \code{\link{setIs}} for the general concept. |
| |
| } |
| \seealso{ |
| \code{\link{showMethods}} prints all the methods for one or more |
| functions. |
| } |
| \examples{ |
| ## following the example shown in the setMethod documentation ... |
| setClass("track", slots = c(x="numeric", y="numeric")) |
| setClass("trackCurve", contains = "track", slots = c(smooth = "numeric")) |
| |
| t1 <- new("track", x=1:20, y=(1:20)^2) |
| |
| tc1 <- new("trackCurve", t1) |
| |
| setMethod("show", "track", |
| function(object)print(rbind(x = object@x, y=object@y)) |
| ) |
| ## The method will now be used for automatic printing of t1 |
| |
| t1 |
| |
| \dontrun{ [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] |
| x 1 2 3 4 5 6 7 8 9 10 11 12 |
| y 1 4 9 16 25 36 49 64 81 100 121 144 |
| [,13] [,14] [,15] [,16] [,17] [,18] [,19] [,20] |
| x 13 14 15 16 17 18 19 20 |
| y 169 196 225 256 289 324 361 400 |
| } |
| ## and also for tc1, an object of a class that extends "track" |
| tc1 |
| |
| \dontrun{ [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] |
| x 1 2 3 4 5 6 7 8 9 10 11 12 |
| y 1 4 9 16 25 36 49 64 81 100 121 144 |
| [,13] [,14] [,15] [,16] [,17] [,18] [,19] [,20] |
| x 13 14 15 16 17 18 19 20 |
| y 169 196 225 256 289 324 361 400 |
| } |
| } |
| \keyword{programming} |