The R Project SVN R

% File src/library/base/man/zMethods.Rd

% Part of the R package, https://www.R-project.org

% Copyright 1995-2026 R Core Team

% Distributed under GPL 2 or later

\name{InternalMethods}

\title{Internal Generic Functions}

\alias{InternalMethods}

\alias{InternalGenerics}

\alias{internal generic}

\alias{.S3PrimitiveGenerics}

\alias{.internalGenerics}

\description{

  Many \R-internal functions are \emph{generic} and allow

  methods to be written for.

}

  % -------------------- grep -nw DispatchOrEval src/*/*[ch]

  %                         --------------

\details{

  The following primitive and internal functions are \emph{generic},

  i.e., you can write \code{\link{methods}} for them:

  % DispatchOrEval internal generic: [

  \code{\link{[}},%            % do_subset()         [subset.c]

  % DispatchOrEval internal generic: [[

  \code{\link{[[}},%           % do_subset2()        [subset.c]

  % DispatchOrEval internal generic: $

  \code{\link{$}},

  % DispatchOrEval internal generic: [<-

  \code{\link{[<-}},

  % DispatchOrEval internal generic: [[<-

  \code{\link{[[<-}},

  % DispatchOrEval internal generic: $<-

  \code{\link{$<-}},

  % DispatchOrEval internal generic: length

  \code{\link{length}},%      % do_length()          [array.c]

  % DispatchOrEval internal generic: length<-

  \code{\link{length<-}},%    % do_lengthgets()      [builtin.c]

  % DispatchOrEval internal generic: lengths

  \code{\link{lengths}},%     % do_lengths()         [array.c]

  % DispatchOrEval internal generic: dimnames

  \code{\link{dimnames}},%    % do_dimnames()        [attrib.c]

  % DispatchOrEval internal generic: dimnames<-

  \code{\link{dimnames<-}},%  % do_dimnamesgets()    [attrib.c]

  % DispatchOrEval internal generic: dim

  \code{\link{dim}},%         % do_dim()             [attrib.c]

  % DispatchOrEval internal generic: dim<-

  \code{\link{dim<-}},%       % do_dimgets()         [attrib.c]

  % DispatchOrEval internal generic: names

  \code{\link{names}},%       % do_names()           [attrib.c]

  % DispatchOrEval internal generic: names<-

  \code{\link{names<-}},%     % do_namesgets()       [attrib.c]

  % DispatchOrEval internal generic: levels<-

  \code{\link{levels<-}},%    % do_levelsgets()      [attrib.c]

  % DispatchOrEval internal generic: @

  \code{\link{@}},%           % do_AT()              [attrib.c]

  % DispatchOrEval internal generic: @<-

  \code{\link{@<-}},%         % do_attrgets()        [attrib.c]

  % DispatchOrEval internal generic: c

  \code{\link{c}},%           % do_c()               [bind.c]

  % DispatchOrEval internal generic: unlist

  \code{\link{unlist}},%      % do_unlist()          [bind.c]

  \code{\link{cbind}},%       not via DispatchOrEval [bind.c]

  \code{\link{rbind}},

  % DispatchOrEval internal generic: as.character

  \code{\link{as.character}},

  % DispatchOrEval internal generic: as.complex

  \code{\link{as.complex}},

  % DispatchOrEval internal generic: as.double

  \code{\link{as.double}},

  % DispatchOrEval internal generic: as.integer

  \code{\link{as.integer}},

  % DispatchOrEval internal generic: as.logical

  \code{\link{as.logical}},

  % DispatchOrEval internal generic: as.raw

  \code{\link{as.raw}},

  % DispatchOrEval internal generic: as.vector

  \code{\link{as.vector}},%    % do_asvector()       [coerce.c]

  % DispatchOrEval internal generic: as.call

  \code{\link{as.call}},%      % do_ascall()         [coerce.c]

  % DispatchOrEval internal generic: as.environment

  \code{\link{as.environment}}%% do_as_environment() [envir.c]

  % DispatchOrEval internal generic: is.array

  \code{\link{is.array}},

  % DispatchOrEval internal generic: is.matrix

  \code{\link{is.matrix}},

  % DispatchOrEval internal generic: is.na

  \code{\link{is.na}},%       % do_isna()            [coerce.c]

  % DispatchOrEval internal generic: anyNA

  \code{\link{anyNA}},%       % do_anyNA()           [coerce.c]

  % DispatchOrEval internal generic: is.nan

  \code{\link{is.nan}},%      % do_isnan()           [coerce.c]

  % DispatchOrEval internal generic: is.finite

  \code{\link{is.finite}}%    % do_isfinite()        [coerce.c]

  % DispatchOrEval internal generic: is.infinite

  \code{\link{is.infinite}}%    % do_isinfinite()    [coerce.c]

  % DispatchOrEval internal generic: is.numeric

  \code{\link{is.numeric}},

  % DispatchOrEval internal generic: nchar

  \code{\link{nchar}}%          % do_nchar()         [character.c]

  % DispatchOrEval internal generic: rep

  \code{\link{rep}},%                                [seq.c]

  % DispatchOrEval internal generic: rep.int

  \code{\link{rep.int}}%        % do_rep_int()       [seq.c]

  % DispatchOrEval internal generic: rep_len

  \code{\link{rep_len}}%        % do_rep_len()       [seq.c]

  % DispatchOrEval internal generic: seq.int

  \code{\link{seq.int}}

  (which dispatches methods for \code{"seq"}),%      [seq.c]

  % DispatchOrEval internal generic: is.unsorted

  \code{\link{is.unsorted}}%    % do_isunsorted()    [sort.c]

  and

  % DispatchOrEval internal generic: xtfrm

  \code{\link{xtfrm}}%                               [sort.c]

  In addition, \code{\link{as.numeric}}

  is a synonym for \code{as.double} and dispatches methods for the

  latter, i.e., S3 methods are for \code{as.double}, whereas S4 methods

  are to be written for \code{as.numeric}.

  Note that all of the \link{group generic} functions are also

  internal/primitive and allow methods to be written for them.

  \code{.S3PrimitiveGenerics} is a character vector listing the

  primitives which are internal generic and not \link{group generic},

  (not only for S3 but also S4).

  Similarly, the \code{.internalGenerics} character vector contains the names

  of the internal (via \code{\link{.Internal}(..)}) non-primitive functions

  which are internally generic.

}

\note{

  For efficiency, internal dispatch only occurs on \emph{objects}, that

  is those for which \code{\link{is.object}} returns true.

}

\seealso{

  \code{\link{methods}} for the methods which are available.

}

\keyword{methods}