Various method to add dynamic accessors (getters/setters)

README.md

Various method to add dynamic accessors (getters/setters)

Make it yourself way

foo = Foo1.new
foo.build1 :a, :b
foo.a = 1
foo.a

foo = Foo1.new
foo.build2 :a, :b
foo.a = 1
foo.a

Open Struct way (only ruby 1.9)

foo = Foo2.new
foo.a = 1
foo.a

Struct way

foo = STRUCT.new
foo.a = 1
foo.a

Benchmark for fun on my extremly slow computer (@work)...

bench.rb

require 'benchmark'
require 'benchmark/ips'
 
load './instance_with_dynamic_accessor.rb'
 
Benchmark.ips do |x|
  x.report("singleton_class") do
    foo = Foo1.new
    foo.build1 :a, :b
    foo.a = 1
    foo.a
  end
  x.report("send") do
    foo = Foo1.new
    foo.build2 :a, :b
    foo.a = 1
    foo.a
  end
  x.report("open_struct") do
    foo = Foo2.new
    foo.a = 1
    foo.a
  end
  x.report("struct") do
    struct = Struct.new :a, :b
    foo = struct.new
    foo.a = 1
    foo.a
  end
end

instance_with_dynamic_accessor.rb

# Make it yourself
class Foo1
  def build1(*args)
    singleton_class.class_eval do
      attr_accessor *args
    end
  end

  def build2(*args)
    self.class.__send__ :attr_accessor, *args
  end
end

# OpenStruct
require 'ostruct'
class Foo2 < OpenStruct
end

# Struct
att = [:a, :b]
STRUCT = Struct.new *att

results.txt

Calculating -------------------------------------
     singleton_class      9595 i/100ms
                send      9920 i/100ms
         open_struct      5868 i/100ms
              struct      7343 i/100ms
-------------------------------------------------
     singleton_class   127811.0 (±7.2%) i/s -     642865 in   5.058452s
                send   124758.9 (±17.2%) i/s -     615040 in   5.071965s
         open_struct    68718.4 (±4.1%) i/s -     346212 in   5.046394s
              struct    87365.2 (±15.9%) i/s -     425894 in   5.076300s