<<-INTRO

Question:
  How fast are these simple use case of memoisation

    hash = {}
    hash[:name] = "Peter"
    hash[:age]  = 23
    hash[:hair_colour] = "black"
    hash

    {}.tap do |hash|
      hash[:name] = "Peter"
      hash[:age]  = 23
      hash[:hair_colour] = "black"
    end

Answer:
  Not really

                       user     system      total        real
  local variable  14.170000   0.060000  14.230000 ( 14.223995)
  tap             15.440000   0.040000  15.480000 ( 15.492474)

INTRO

require 'memoist'

class Foo
  extend Memoist

  def memoized
    42
  end
  memoize :memoized

  def memoized_manually
    @memoized_manually ||= 42
  end

  def memoized_manually_with_defined
    unless defined?(@memoized_manually_with_defined)
      @memoized_manually_with_defined = 42
    end
    @memoized_manually_with_defined
  end

  def raw
    42
  end

  def memoized_with_arg(arg)
    42
  end
  memoize :memoized_with_arg
end

require 'benchmark'

TIMES = 10_000_000

Benchmark.bm(40) do |x|
  x.report "calling memoized method" do
    foo = Foo.new
    TIMES.times do
      foo.memoized
    end
  end

  x.report "calling manually memoized method" do
    foo = Foo.new
    TIMES.times do
      foo.memoized_manually
    end
  end
  
  x.report "calling manually memoized (with defined?) method" do
    foo = Foo.new
    TIMES.times do
      foo.memoized_manually_with_defined
    end
  end
  
  x.report "calling non-memoized method" do
    foo = Foo.new
    TIMES.times do
      foo.raw
    end
  end

  x.report "calling memoized method - one time" do
    TIMES.times do
      foo = Foo.new
      foo.memoized
    end
  end

  x.report "calling manually memoized method - one time" do
    TIMES.times do
      foo = Foo.new
      foo.memoized_manually
    end
  end

  x.report "calling manually memoized (with defined?) method - one time" do
    TIMES.times do
      foo = Foo.new
      foo.memoized_manually_with_defined
    end
  end

  x.report "calling non-memoized method - one time" do
    TIMES.times do
      foo = Foo.new
      foo.raw
    end
  end
  x.report "re-loading memoized method" do
    foo = Foo.new
    TIMES.times do
      foo.memoized(true)
    end
  end
  
  comment = <<-COMMENT
  
  x.report "calling memoized method with args" do
    foo = Foo.new
    TIMES.times do
      foo.memoized_with_arg(1337)
    end
  end
  
  x.report "calling memoized method with args - no cache" do
    foo = Foo.new
    TIMES.times do |i|
      foo.memoized_with_arg(i)
    end
  end

  COMMENT

end