Programming Ruby 3.3

OpenStruct

If Data is the most immutable way to get a small object, OpenStruct is the most flexible. An OpenStruct isn’t a class generator, rather, it’s more a way to allow you to have hash-like data with attribute-like syntax.

You create an OpenStruct with new method, taking either a hash argument or an arbitrary set of keyword arguments. After that, you can read, write, and create attributes just by using them, and you can also use hash syntax:

require "ostruct"

bulb = OpenStruct.new(brightness: 1600, watts: 15, color: 2500)
bulb.color   # => 2500
bulb[:watts] # => 15
bulb.shape = "A19"
bulb.to_h    # => {:brightness=>1600, :watts=>15, :color=>2500, :shape=>"A19"}

Internally OpenStruct uses method_missing, which ...