1\name{Rdo_get_args} 2\alias{Rdo_get_args} 3\alias{Rdo_get_arg} 4\title{ 5 Extract argument description from a help topic 6} 7\description{ 8 Extract argument description from a help topic. 9} 10\usage{ 11Rdo_get_args(rd, args, ...) 12Rdo_get_arg(rd, arg) 13} 14\arguments{ 15 \item{rd}{the documentation for the topic, typically an Rd object but 16 may be anything that \code{\link{Rd_fun}} accepts.} 17 \item{arg}{an argument name, a string} 18 \item{args}{names of arguments to describe, a character vector, see 19 also Details section} 20 \item{\dots}{not used} 21} 22\details{ 23 If \code{arguments} is missing, descriptions of all arguments are 24 returned. 25 26 Effort is made to handle the case when two or more arguments are 27 described in a single entry. In that case it is not possible to 28 disentangle the description automatically. So, the description is 29 returned as is. Also, only one copy of the description is returned, 30 see the examples with the \code{from} and \code{to} arguments of 31 function \code{seq}. 32 33 The \code{...} argument is handled, as well, give it as the string 34 \verb{...} in \code{args}. 35 36 \code{Rdo_get_arg} simply calls \code{Rdo_get_args} and returns the 37 first element of its value. This means that \code{arg} is expected to 38 be of length one, but this is not enforced. Note also that 39 \code{Rdo_get_arg} is not completely equivalent to calling 40 \code{Rdo_get_args} with \code{length(args)=1}. 41} 42\value{ 43 For \code{Rdo_get_args}, an Rd fragment representing the (part of) 44 help section \verb{\arguments} containing descriptions of the requested 45 arguments. 46 47 For \code{Rdo_get_arg} an Rd fragment representing the help for a 48 single argument. 49} 50% \references{ 51% %% ~put references to the literature/web site here ~ 52% } 53% \author{ 54% %% ~~who you are~~ 55% } 56\author{Georgi N. Boshnakov} 57% \note{ 58% %% ~~further notes~~ 59% } 60% 61% %% ~Make other sections like Warning with \section{Warning }{....} ~ 62% 63% \seealso{ 64% %% ~~objects to See Also as \code{\link{help}}, ~~~ 65% } 66\examples{ 67h1 <- help("seq") 68Rdo_get_args(h1) 69Rdo_get_args(h1,"by") 70Rdo_get_args(h1,"length.out") 71Rdo_get_args(h1,"...") 72Rdo_get_args(h1,"from") 73Rdo_get_args(h1,c("from","by")) 74Rdo_get_args(h1,c("from", "to")) 75 76Rdo_get_args("seq") 77Rdo_get_args("seq","by") 78Rdo_get_args("seq","length.out") 79Rdo_get_args("seq","...") 80Rdo_get_args("seq","from") 81Rdo_get_args("seq",c("from","by")) 82Rdo_get_args("seq",c("from", "to")) 83} 84\keyword{ Rd } 85