####Modules
image_utils.rb
module ImageUtils
def preview
puts "preview"
end
def transfer(url)
puts "transfer #{url}"
end
end
image.rb (关键字 include)
require './image_utils'
class Image
include ImageUtils
end
run.rb
require './image'
image = Image.new
image.preview //preview
image.transfer("mlx") //transfer mlx
include后 实例化可调用 即为 实例方法
image.rb (关键字 extend)
require './image_utils'
class Image
extend ImageUtils
end
run.rb
require './image'
Image.preview //preview
Image.transfer("mlx") //transfer mlx
extend后 直接调用 类方法
puts Image.ancestors //输出Image的所有父类
puts Image.included_modules //输出Image所include的module
用include实现多继承 （ruby是单继承的）
