register_method {bandicoot}

Register method for an object environment

Description

This function register a function as a method of an object environment.

Usage

register_method(
  env,
  ...,
  container_name = "..method_env..",
  self_name = "self",
  class_name = env$..type..
)

Arguments

env

Environment. Object environment.

...

Named Functions. Functions needs to be provided in named format, like a = function() 1.

container_name

Character. Name of the container. Methods will be executed inside this container.

self_name

Character. Name of the self reference. Methods needs to use this name to access the object environment.

class_name

Character. Name of the class of the object environment. This is important for super() to resolve the correct parent class.

Details

Methods will be executed inside a container, which is a child environment of the parent of the object environment. Thus, methods can not access variables of the object environment directly, but can access variables of the parent of the object environment directly. The designed way for methods to access the object environment is by using the name "self", this name can be changed by specifying a string in self_name. The default name of the container is "..method_env..". This also can be changed by specifying a string in container_name. An object can have multiple containers, but every container is recommended to contain only one self reference.

Method needs to be provided as a = function() 1, where a is the name of the method and the right hand side of the equal sign is the function. Warning will be raised if the container contains contents other than the self reference.

Value

Return the object itself.

Examples

a <- function() self$x

e <- new.env()
e$x <- 1

# Register the method `aa` for environment `e` with `self_name = "self"`
register_method(e, aa = a, self_name = "self", class_name = "test")

# There is an environment `..method_env..` in the environment `e`
names(e)

# The container is empty (except `self`)
names(e$..method_env..)

# `self` is a reference to `e`
identical(e, e$..method_env..$self)

# The method `aa` will be evaluated in the container
identical(environment(e$aa), e$..method_env..)

# Therefore, `self$x` is a reference to variable `x` of the environment `e`
e$aa()