templates: Extend constructive

In constructive: Display Idiomatic Code to Construct Most R Objects

Extend constructive

Description

.cstr_new_class() and .cstr_new_constructor() open new unsaved scripts, optionally commented, that can be used as templates to define new constructors. If the class is already supported and you want to implement a new constructor, use .cstr_new_constructor(), otherwise use .cstr_new_class().

Usage

.cstr_new_class(
  class = c("CLASS", "PARENT_CLASS"),
  constructor = "PKG::CONSTRUCTOR",
  commented = FALSE
)

.cstr_new_constructor(
  class = c("CLASS", "PARENT_CLASS"),
  constructor = "PKG::CONSTRUCTOR",
  commented = FALSE
)

Arguments

class	Class to support, provide the full class() vector.
constructor	Name of the constructor, usually the name of the function you can to use to build the object. If not you might need to adjust the script.
commented	Boolean. Whether to include comments in the template.

Details

We suggest the following workflow (summarized in a message when you call the functions):

• Call ⁠usethis::use_package(\"constructive\"⁠, \"Suggests\")' one time at any point, this will add a soft dependency on 'constructive' so it's only needed to install it when you use it.

• Call .cstr_new_class() or .cstr_new_constructor(), with commented = TRUE for more guidance.

• Save the scripts unchanged in the "R" folder of your package.

• devtools::document(): this will register the S3 methods.

• Try construct() on your new object, it should print a call to your chosen constructor.

• Tweak the code, in particular the definition of args.

The README of the example extension package 'constructive.example' guides you through the process. See also {constructive}'s own code and vignette("extend-constructive") for more details.

Value

Both function return NULL invisibly and are called for side effects

constructive documentation built on April 3, 2025, 9:39 p.m.