newObject: An object constructor of an S3 class

In paodan/funcTools: some useful function tools in practice

An object constructor of an S3 class

Description

This is inspired by the object oriented programming in Javascript and ggproto function/object in ggplot2 package. Here the attributes of the object are replaced in place, and it is able to access the object it"self" and its parent object in the method of this object.

Usage

newObject(`_class` = NULL, `_inherit` = NULL, pos = 1, ...)

Arguments

pos	into which environment the $ method (see value part) is assigned. The pos argument can specify the environment in which to assign the object in any of several ways: as a positive integer (the position in the search list, default is 1); as the character string name of an element in the search list; or as an environment (including using sys.frame to access the currently active function calls).
`_class`	of which class an object to create
`_inherit`	the parent class an object to inherit

Value

an instance of '_class' object. Meanwhile, an S3 method of '$' function is generated in the same environment of the object that you just constructed. For example, if the "NewClass" is assigned to '_class' parameter, then a function/method called $.NewClass is constructed.

Examples

## Not run: 
Adder <- newObject("Adder", 
                   x = 0,
                   add = function(n) {
                     self$x <- self$x + n
                     self$x
                   }
)
Adder$x
Adder$add(10)
# Adder$x is replaced in place
Adder$add(10)

Doubler <- newObject("Doubler", Adder,
                     add = function(n) {
                       self$x = self$x *(n) * self$super()$x
                       self$x
                     }
)
Doubler$x
Adder$x
Doubler$add(10)
Doubler$self()

identical(Adder, Doubler$super())
Adder$self() # Adder
Doubler$super()$self() # Adder

# update Adder
Adder$add(10)
Adder$x
# the super of Doubler is also update
Doubler$super()$x
# But Double itself is not changed
Doubler$x

## End(Not run)

paodan/funcTools documentation built on April 1, 2024, 12:01 a.m.