动态设置类变量所使用到的方法为:class_variable_set和class_variable_get。实例: class Person (1..3).each do |num| class_variable_set("@@name_#{num}".to_sym, num * 3) end def initialize (1..3).each do |num| instance_variable_set("@name_#{num}".to_sym, self.class.class_variab...
p obj.instance_variable_set("@foo",1)# => 1 p obj.instance_variable_set(:@foo,2)# => 2 p obj.instance_variable_get(:@foo)# => 2
class_eval do define_method "#{attribute}=" do |value| instance_variable_set("@#{attribute}", value) end define_method attribute do instance_variable_get "@#{attribute}" end end end add_checked_attribute(Person, :age) add_checked_attribute(Person, :sex) me = Person.new me.age = 18...
由于两种方法非常常用,Ruby 定义了attr_accessor :variable_name、attr_reader :variable_name、attr_writer :variable_name三种属性声明方法。其中:accessor=reader+writer。 同时注意:变量名前一定要带:,变量名之间要用,分割。 实例方法 实例方法的定义与其他方法的定义一样,都是使用def关键字,但它们只能通过类实例来...
A setter method is one which sets, or changes, the value of a variable belonging to a particular object. Alright, let’s check in on yourusername. If my math is correct, it should be set to“coolgirl2002”right now. julia.username#NoMethodError: undefined method `username' for #<User:...
This is a new C-API set to exchange a raw memory area, such as a numeric array and a bitmap image, between extension libraries. The extension libraries can share also the metadata of the memory area that consists of the shape, the element format, and so on. Using these kinds of metad...
An instance variable set within a before validator is accessible within the endpoint's code and can also be utilized within the rescue_from handler. class TwitterAPI < Grape::API before do @var = 1 end get '/' do puts @var # => 1 raise end rescue_from :all do puts @var # => ...
Here we use Ruby’sinstance_variable_getmethod to read an instance variable with an arbitrary name, andinstance_variable_setto assign a new value to it. Unfortunately the variable name must be prefixed with an “@” sign in both cases—hence the string interpolation. ...
It is currently autoloaded via the Set constant or a call to Enumerable#to_set. String String#byteindex and String#byterindex have been added. [Feature #13110] Update Unicode to Version 15.0.0 and Emoji Version 15.0. [Feature #18639] ...
==>120puts'Too long!'Time.now.hour>21puts.name=='Misty'puts'Not again!'whensong.duration>120puts'Too long!'whenTime.now.hour>21puts"It's too late"elsesong.playend This is the style established in both "The Ruby Programming Language" and "Programming Ruby". Historically it is derived ...