Ruby中的方法和属性有什么区别？

Question

能给我举个例子？

Answer 1

属性只是一种捷径.如果您使用attr_accessor创建属性,Ruby只会声明一个实例变量并为您创建getter和setter方法.

既然你问了一个例子:

class Thing
    attr_accessor :my_property

    attr_reader :my_readable_property

    attr_writer :my_writable_property

    def do_stuff
        # does stuff
    end
end 

以下是您使用该课程的方法:

# Instantiate
thing = Thing.new

# Call the method do_stuff
thing.do_stuff

# You can read or write my_property
thing.my_property = "Whatever"
puts thing.my_property

# We only have a readable accessor for my_readable_property
puts thing.my_readable_property 

# And my_writable_propety has only the writable accessor
thing.my_writable_property = "Whatever"

Answer 2

属性是对象的特定属性.方法是对象的功能.

在Ruby中,默认情况下所有实例变量(属性)都是私有的.这意味着您无法在实例本身范围之外访问它们.访问该属性的唯一方法是使用访问器方法.

class Foo
  def initialize(color)
    @color = color
  end
end

class Bar
  def initialize(color)
    @color = color
  end

  def color
    @color
  end
end

class Baz
  def initialize(color)
    @color = color
  end

  def color
    @color
  end

  def color=(value)
    @color = value
  end
end

f = Foo.new("red")
f.color # NoMethodError: undefined method ‘color’

b = Bar.new("red")
b.color # => "red"
b.color = "yellow" # NoMethodError: undefined method `color=' 

z = Baz.new("red")
z.color # => "red"
z.color = "yellow"
z.color # => "yellow"

因为这是一个非常commmon行为,Ruby提供了一些方便的方法来定义存取方法:attr_accessor,attr_writer和attr_reader.