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R.oo (version 1.2.7)

isBeingCreated.Class: Checks if a class is currently being initiated initiated

Description

Checks if a class is currently being initiated initiated. When extending a class for the first time, which is typically done in a constructor, a static instance of the class is created by calling the constructor without parameters. This method provides a way to detect that second call inside the constructor.

Usage

## S3 method for class 'Class}(this, ...)':
isBeingCreatedundefined

...{Not used.}

Returns TRUE if a static instance exists, otherwise FALSE.

setConstructorS3("Car", function(brand=NULL, nbrOfWheels=0) {
  if(!isBeingCreated(Car)) {
    if (is.null(brand))
      throw("A car must have a brand")
     
    if (nbrOfWheels <= 0)="" throw("a="" car="" must="" have="" one="" or="" more="" wheels:="" ",="" nbrofwheels)="" }="" extend(object(),="" "car",="" .brand="brand," .nbrofwheels="nbrOfWheels" )="" })="" setmethods3("as.character",="" function(this,="" ...)="" {="" cat(class(this)[1],="" ":",="" this$.brand,="" "="" with="" this$.nbrofwheels,="" wheels.",="" sep="" );="" print(car("volvo",="" 4))="" print(car("bmw",="" print(car("tyrrell="" p34",="" 6))="" print(car("t-rex",="" 3))<="" examples="">

[object Object]

For more information see Class.



internal
methods
programming

Arguments