Produce the textual form of the signatures of available methods for an S4 generic function

Produce the textual form of the signatures of available methods for an S4 generic function.

Usage

get_sig_text(rdo, package = NULL)

Arguments

rdo

an Rd object.

package

if of class "character", give only methods defined by package, otherwise give all methods.

Details

Signatures are found using function findMethodSignatures from package "methods".

Here we find all methods for show() defined in package "methods" and print the first few of them: fn <- utils::help("show-methods", package = "methods"); rdo <- utils:::.getHelpFile(fn); head(get_sig_text(rdo))

Value

A character vector with one element for each method.

Author

Georgi N. Boshnakov

Note

todo: It would be better to call promptMethods() to get the signatures but in version R-2.13.x I had trouble with argument `where' (could not figure out how to use it to restrict to functions from a package; also, promptMethods() seemed to call the deprecated function getMethods()). Check how these things stand in current versions of R, there may be no problem any more (checked, in 2.14-0 it is the same).

Examples

## load another package with some S4 methods ("methods" is already loaded)
require("stats4") 

rdo <- Rdo_fetch("show", package = "methods")
## alternatively:
#fn <- help("show-methods", package = "methods")
#rdo <- utils:::.getHelpFile(fn)

## this will find all methods for "show" in currently loaded packages
## (print only some of them)
head(get_sig_text(rdo))
#> [1] "signature(object = \"ANY\")"                      
#> [2] "signature(object = \"MethodDefinition\")"         
#> [3] "signature(object = \"MethodDefinitionWithTrace\")"
#> [4] "signature(object = \"MethodSelectionReport\")"    
#> [5] "signature(object = \"MethodWithNext\")"           
#> [6] "signature(object = \"MethodWithNextWithTrace\")"  

## this will select only the ones from package "stats4"
get_sig_text(rdo, package = "stats4")
#> [1] "signature(object = \"mle\")"         "signature(object = \"summary.mle\")"

## this is also fine (interactively) but need to choose
## the appropriate element of "fn" if length(fn) > 1
#fn <- help("show-methods")

## this finds nothing
#fn <- help("logLik-methods", package = "methods")
#fn
Rdo_fetch("logLik-methods", package = "methods")
#> NULL

## this does
#fn <- help("logLik-methods", package = "stats4")
#rdo <- utils:::.getHelpFile(fn)
rdo2 <- Rdo_fetch("logLik-methods", package = "stats4")

get_sig_text(rdo2)
#> [1] "signature(object = \"ANY\")" "signature(object = \"mle\")"
get_sig_text(rdo2, package = "stats4")
#> [1] "signature(object = \"ANY\")" "signature(object = \"mle\")"

## only default method defined
## using this:
setGeneric("f1", function(x, y){NULL})
#> [1] "f1"
## since the following gives error in pkgdown:
#f1 <- function(x, y){NULL}
#setGeneric("f1")

fn <- tempfile()

reprompt("f1", filename = fn)
#> Rd source not supplied, looking for installed documentation.
#> Rd source not supplied and installed documentation not found.
#> Trying a 'prompt' function to generate documentation for the object.
#> 	success: documentation generated using a 'prompt' function.
#> 	The Rd content was written to file  /tmp/RtmpnmJSSB/file16ad42b1a958 
#> [1] "/tmp/RtmpnmJSSB/file16ad42b1a958"
rdo <- tools::parse_Rd(fn)
get_sig_text(rdo)
#> [1] "signature(x = \"ANY\")"

setClass("aRdpack")
setClass("bRdpack")

## several methods defined
setGeneric("f4", function(x, y){NULL})
#> [1] "f4"
setMethod("f4", c("numeric", "numeric"), function(x, y){NULL})
setMethod("f4", c("aRdpack", "numeric"), function(x, y){NULL})
setMethod("f4", c("bRdpack", "numeric"), function(x, y){NULL})
setMethod("f4", c("aRdpack", "bRdpack"), function(x, y){NULL})

reprompt("f4", filename = fn)
#> Rd source not supplied, looking for installed documentation.
#> Rd source not supplied and installed documentation not found.
#> Trying a 'prompt' function to generate documentation for the object.
#> 	success: documentation generated using a 'prompt' function.
#> 	The Rd content was written to file  /tmp/RtmpnmJSSB/file16ad42b1a958 
#> [1] "/tmp/RtmpnmJSSB/file16ad42b1a958"
rdo <- tools::parse_Rd(fn)
get_sig_text(rdo)
#> [1] "signature(x = \"ANY\", y = \"ANY\")"        
#> [2] "signature(x = \"aRdpack\", y = \"bRdpack\")"
#> [3] "signature(x = \"aRdpack\", y = \"numeric\")"
#> [4] "signature(x = \"bRdpack\", y = \"numeric\")"
#> [5] "signature(x = \"numeric\", y = \"numeric\")"

unlink(fn)