R/createInstance.r

In rappster/classr: Class instances for rapid prototyping

#' @title
#' Create Class Instance
#'
#' @description 
#' Creates an instance of a specific class.
#'   	
#' @param cl \strong{Signature argument}.
#'    Object containing class information.
#'    This usually corresponds to the name of a class.
#' @param input \strong{Signature argument}.
#'    Object containing object information that is relevant in the context
#'    of instantiating.
#'    This usually corresponds to an object that should be used "as is" as the 
#'    actual instance object and for which only the class path should be 
#'    updated.
#' @param strict \code{\link{logical}}.
#'    \code{TRUE}: error if \code{cl} is not a class (checked by \code{isClass});
#'    \code{FALSE}: no class existence check.
#' @template threedot
#' @example inst/examples/createInstance.r
#' @seealso \code{
#'   	\link[classr]{createInstance-missing-method}
#' }
#' @template author
#' @template references
#' @export 

setGeneric(
  name = "createInstance",
  signature = c(
    "cl",
    "input"
  ),
  def = function(
    cl,
    input = new.env(parent = emptyenv()),
    strict = FALSE,
    ...
  ) {
    standardGeneric("createInstance")       
  }
)

#' @title
#' Create Class Instance
#'
#' @description 
#' See generic: \code{\link[classr]{createInstance}}
#'      
#' @inheritParams createInstance
#' @param cl \code{\link{character}}.
#' @param input \code{\link{missing}}.
#' @return See method 
#'    \code{\link{createInstance-character-ANY}}.
#' @example inst/examples/createInstance.r
#' @seealso \code{
#'    \link[classr]{createInstance}
#' }
#' @template author
#' @template references
#' @export

setMethod(
  f = "createInstance", 
  signature = signature(
    cl = "character",
    input = "missing"
  ), 
  definition = function(
    cl,
    input,
    strict,
    ...
  ) {

  createInstance(
    cl = cl,
    input = input,
    strict = strict,
    ...
  )
    
  }
)

#' @title
#' Create Class Instance
#'
#' @description 
#' See generic: \code{\link[classr]{createInstance}}
#'   	 
#' @inheritParams createInstance
#' @param cl \code{\link{character}}.
#' @param cl \code{\link{ANY}}.
#' @return \code{\link{ANY}}. Either \code{input} with modified class path or
#'    an object that is actually an empty \code{\link{environment}} but has an 
#'    updated class path with class \code{cl} being the first element.
#' @example inst/examples/createInstance.r
#' @seealso \code{
#'    \link[classr]{createInstance}
#' }
#' @template author
#' @template references
#' @export

setMethod(
  f = "createInstance", 
  signature = signature(
    cl = "character",
    input = "ANY"
  ), 
  definition = function(
    cl,
    input,
    strict,
    ...
  ) {

  if (strict) {
    if (!isClass(cl)) {
      stop(paste0("[", Sys.getpid(), "] ", gsub("-|:| ", "", Sys.time()), 
         "/classr/createInstance> Not a class: ", cl))
    }
  }
  class(input) <- unique(c(cl, class(input)))
  input
    
  }
)