describe_function {svMisc}

Get textual help on function or function arguments, or get a call tip

Description

Textual help on functions or their arguments is extracted for text online help for a given function. By default, all arguments from the online help are returned for describe_args(). If the file contains help for several functions, one probably gets also some irrelevant information. Use of 'args' to limit result is strongly encouraged. args_tip() provides a human-readable textual description of function arguments in a better way than args() does. It is primarily intended for code tips in GUIs. call_tip() has a similar purpose to show how some code could be completed.

Usage

describe_function(fun, package, lib.loc = NULL)

describe_args(fun, args = NULL, package = NULL, lib.loc = NULL)

args_tip(name, only.args = FALSE, width = getOption("width"))

call_tip(
  code,
  only.args = FALSE,
  location = FALSE,
  description = FALSE,
  methods = FALSE,
  width = getOption("width")
)

descFun(fun, package, lib.loc = NULL)

descArgs(fun, args = NULL, package = NULL, lib.loc = NULL)

argsTip(name, only.args = FALSE, width = getOption("width"))

callTip(
  code,
  only.args = FALSE,
  location = FALSE,
  description = FALSE,
  methods = FALSE,
  width = getOption("width")
)

Arguments

fun

A character string with the name of a function (several functions accepted too for describe_function().

package

A character string with the name of the package that contains fun, or NULL for searching in all loaded packages.

lib.loc

A character vector of directory names of R libraries, or NULL. The default value of NULL corresponds to all libraries currently known. If the default is used, the loaded packages are searched before the libraries.

args

Either NULL (by default) to return the description of all arguments from the corresponding man page, or a character vector with names of the arguments to search for.

name

A string with the name of a function.

only.args

Do we return only arguments of the function (⁠arg1, arg2 = TRUE, ...⁠), or the full call, like (myfun(arg1, arg2 = TRUE, ...)).

width

Reformat the tip to fit to fit in that width, except if width = NULL.

code

A fraction of R code ending with the name of a function, eventually followed by '('.

location

If TRUE then the location (in which package the function resides) is appended to the calltip between square brackets.

description

If TRUE then a short description of the function is added to the call_tip (in fact, the title of the corresponding help page, if it exists).

methods

If TRUE then a short message indicating if this is a generic function and that lists, in this case, available methods.

Value

A string with the description of the function or of its arguments, or the calling syntax of the function, plus additional information depending on the flags used. If the man page is not found, a vector of empty strings is returned. Empty strings are also returned for arguments that are not found in the man page.

Note

args_tip() is supposed to display S3 and S4 methods, and primitives adequately,... but this is not implemented yet in the current version! For call_tip(), the use of methods = TRUE slows down the execution of the function, especially for generic functions that have many methods like print() or summary().

See Also

completion(), args(), argsAnywhere()

Examples

describe_function("ls", "base")
describe_function("library", "base")
describe_function("descFun", "svMisc")
describe_function("descArgs")

describe_args("ls")
describe_args("library", args = c("package", "pos"))

args_tip("ls")

call_tip("myvar <- lm(")