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\name{parse_pairlist}
\alias{parse_pairlist}
%\alias{pairlist2f_usage}
\alias{pairlist2f_usage1}
\title{
Parse formal arguments of functions
\Sexpr[stage=build,results=hide]{require(Rdpack)}
}
\description{Parse formal arguments of functions and convert them to
f_usage objects.}
\usage{
parse_pairlist(x)
pairlist2f_usage1(x, name, S3class = "", S4sig = "", infix = FALSE,
fu = TRUE)
}
\arguments{
\item{x}{a pairlist representing the arguments of a function.}
\item{name}{function name.}
\item{S3class}{S3 class, see `Details'}
\item{S4sig}{S4 signature, see Details.}
\item{infix}{if \code{TRUE} the function usage is in infix form, see
Details.}
\item{fu}{if TRUE the object is a function, otherwise it is something
else (e.g. a variable or a constant like \code{pi} and \code{Inf}).
}
}
\details{
These functions are mostly internal.
% \code{x} is a single pairlist object for \code{parse_pairlist} and
% \code{pairlist2f_usage1}.
% For \code{pairlist2f_usage} it may be a list of pairlist objects.
% (\code{pairlist2f_usage} has been removed)
\code{parse_pairlist} parses the pairlist object, \code{x}, into a
list with two components. The first component contains the names of
the arguments. The second component is a named list containing the
default values, converted to strings. Only arguments with default
values have entries in the second component (so, it may be of length
zero). If \code{x} is empty or \code{NULL}, both components have
length zero. An example:
\printExample{parse_pairlist(formals(system.file))}
\code{pairlist2f_usage1()} creates an object of S3 class
\code{"f_usage"}. The object contains the result of parsing \code{x}
with \code{parse_pairlist(x)} and a number of additional components
which are copies of the remaining arguments to the function (without
any processing). The components are listed in section Values.
\code{S3class} is set to an S3 class for for S3 methods, \code{S4sig}
is the signature of an S4 method (as used in Rd macro
\verb{\S4method}). \code{infix} is \code{TRUE} for the rare occations
when the function is primarily used in infix form.
Class \code{"f_usage"} has a method for \code{as.character()} which
generates a text suitable for inclusion in Rd documentation.
\printExample{pairlist2f_usage1(formals(summary.lm), "summary", S3class = "lm")}
}
\value{
For \code{parse_pairlist}, a list with the following components:
\item{argnames}{the names of all arguments, a character vector}
\item{defaults}{
a named character vector containing the default values, converted to
character strings. Only arguments with defaults have entries in this
vector.
}
For \code{pairlist2f_usage1}, an object with S3 class
\code{"f_usage"}. This is a list as for \code{parse_pairlist} and
the following additional components:
\item{name}{function name, a character string.}
\item{S3class}{
S3 class, a character string; \code{""} if not an S3 method.
}
\item{S4sig}{S4 signature; \code{""} if not an S4 method.}
\item{infix}{a logical value, \code{TRUE} for infix operators.}
\item{fu}{
indicates the type of the object, usually \code{TRUE}, see Details.
}
% For \code{pairlist2f_usage}, a list of \code{"f_usage"} objects.
}
\author{Georgi N. Boshnakov}
\seealso{
\code{\link{promptUsage}} accepts \code{f_usage} objects,
\code{\link{get_usage}}
}
\examples{
parse_pairlist(formals(lm))
parse_pairlist(formals(system.file))
s_lm <- pairlist2f_usage1(formals(summary.lm), "summary", S3class = "lm")
s_lm
as.character(s_lm)
}
\keyword{RdoBuild}
|
