module Gitlab
# A class that can be wrapped around an expensive method call so it's only
# executed when actually needed.
#
# Usage:
#
# object = Gitlab::Lazy.new { some_expensive_work_here }
#
# object['foo']
# object.bar
class Lazy < BasicObject
def initialize(&block)
@block = block
end
def method_missing(name, *args, &block)
__evaluate__
@result.__send__(name, *args, &block)
end
def respond_to_missing?(name, include_private = false)
__evaluate__
@result.respond_to?(name, include_private) || super
end
private
def __evaluate__
@result = @block.call unless defined?(@result)
end
end
end