scope_test.rb

#!/usr/bin/env ruby

# https://gist.github.com/3957219

@cache = nil

def hoge
  @cache ||= Proc.new {
    fuga = piyo()
    "result: #{fuga}"
  }.call
end

def piyo
  puts "called piyo"
  return 42
end

puts hoge()
puts hoge()
puts hoge()