Ruby - 从任意类/模块中获取常量

Question

我有两个班级：

class Ios 
  REST_ENDPOINT = 'http://rest'
  SOAP_ENDPOINT = 'http://soap'
end

class Android
  REST_ENDPOINT = 'http://rest'
  SOAP_ENDPOINT = 'http://soap'
end

然后我有两个REST和SOAP类：

class REST
  def some_action
    # I want to use the endpoint based on device type
  end
end


class SOAP
  def some_action
    # I want to use the endpoint based on device type 
  end
end

如何在REST和SOAP类中使用基于设备类型的end_point URL？

此致 Kayen

Answer 1

这是你想要实现的目标吗？

class REST
  def some_action
    ios_url = URI.parse("#{Ios::REST_ENDPOINT}/login")
    android_url = URI.parse("#{Android::REST_ENDPOINT}/login")
  end
end

class SOAP
  def some_action
    ios_url = URI.parse("#{Ios::SOAP_ENDPOINT}/login")
    android_url = URI.parse("#{Android::SOAP_ENDPOINT}/login")
  end
end

你也可以使用这样的重构：

密新

module Endpoints

  def initialize device = Ios
    @device = device_class(device)
  end

  def url device = nil
    URI.parse "#{endpoint(device || @device)}/login"
  end

  def ios_url
    URI.parse "#{endpoint Ios}/login"
  end

  def android_url
    URI.parse "#{endpoint Android}/login"
  end

  private
  def endpoint device
    device_class(device).const_get self.class.name + '_ENDPOINT'
  end

  def device_class device
    device.is_a?(Class) ? 
      device : 
      Object.const_get(device.to_s.capitalize)
  end

end

在课程中包含Mixin

class REST
  include Endpoints

  def some_action
    # use ios_url and android_url here
  end
end

class SOAP
  include Endpoints

  def some_action
    # use ios_url and android_url here
  end
end

一些测试：

puts REST.new(:Ios).url
#=> http://ios-rest.com/login

puts REST.new.url :Ios
#=> http://ios-rest.com/login

puts REST.new.ios_url
#=> http://ios-rest.com/login


puts REST.new(:Android).url
#=> http://android-rest.com/login

puts REST.new.url :Android
#=> http://android-rest.com/login

puts SOAP.new.android_url
#=> http://android-soap.com/login

Here是一个有效的演示