The R Project SVN R

% Copyright 1995-2012 R Core Team

% Copyright 1995-2016 R Core Team

findMethod(f, signature, where)

  findMethod(f, signature, where)

selectMethod(f, signature, optional = FALSE, useInherited =,

   getMethod(f, signature = character(), where, optional = FALSE, mlist, fdef)

hasMethod(f, signature=character(), where)

   hasMethod(f, signature = character(), where)

  \item{f}{A  generic function or the character-string name of one.}

  \item{f}{a generic function or the character-string name of one.}

    of \code{f}.  See the details below.

    of \code{f}.  See the details below.}

  \item{where}{The position or environment in which to look for the

  \item{where}{the position or environment in which to look for the

    method(s):  by default, the table of methods defined in the generic function itself is used.}

    method(s):  by default, the table of methods defined in the generic

  \item{optional}{If the selection in \code{selectMethod} does not find a valid method

  \item{optional}{if the selection in \code{selectMethod} does not find

    an error is generated, unless this argument is \code{TRUE}.  In that

    a valid method an error is generated, unless \code{optional} is

    case, the value returned is \code{NULL} if no method matches.}

    true.  In that case, the value returned is \code{NULL} if no method

  \item{mlist, fdef, useInherited, verbose, doCache}{Optional

  \item{mlist, fdef, useInherited, verbose, doCache}{optional arguments

      arguments  to  \code{getMethod} and \code{selectMethod} for

    to  \code{getMethod} and \code{selectMethod} for internal use.  Avoid

      internal use.  Avoid

    these: some will work as expected and others will not, and none of

      these: some will work as expected and others will not, and none of them is required for normal use of the functions.

    them is required for normal use of the functions.}

  The \code{signature} argument specifies classes, corresponding to formal arguments of the generic function; to be precise, to the \code{signature} slot of the generic function object.

  The \code{signature} argument specifies classes, corresponding to

    The argument may be a vector of strings identifying

  formal arguments of the generic function; to be precise, to the

    classes, and may be named or not.  Names, if supplied, match the

  may be a vector of strings identifying classes, and may be named or

    names of those formal arguments included in the signature of the

  not.  Names, if supplied, match the names of those formal arguments

    generic.  That signature is normally all the arguments except

  included in the signature of the generic.  That signature is normally

    \dots.  However, generic functions can be specified with only a

  all the arguments except \dots.  However, generic functions can be

    subset of the arguments permitted, or with the signature taking

  specified with only a subset of the arguments permitted, or with the

    the arguments in a different order.

  signature taking the arguments in a different order.

    It's a good idea to name the arguments in the signature to avoid

  It's a good idea to name the arguments in the signature to avoid

    confusion, if you're dealing with a generic that does something

  confusion, if you're dealing with a generic that does something

    special with its signature.   In any case, the elements of the

  special with its signature.  In any case, the elements of the

    signature are matched to the formal signature by the same rules

  signature are matched to the formal signature by the same rules used

    used in matching arguments in function calls (see

  in matching arguments in function calls (see

    \code{\link{match.call}}).

  \code{\link{match.call}}).

    The strings in the signature may be class names, \code{"missing"}

  The strings in the signature may be class names, \code{"missing"} or

    or \code{"ANY"}.  See \link{Methods} for the meaning of these in

  \code{"ANY"}.  See \link{Methods} for the meaning of these in method

    method selection.  Arguments not supplied in the signature

  selection.  Arguments not supplied in the signature implicitly

    implicitly correspond to class \code{"ANY"}; in particular, giving

  correspond to class \code{"ANY"}; in particular, giving an empty

    an empty signature means to look for the default method.

  signature means to look for the default method.