Ruby：根据用户输入动态定义类答案

【问题标题】：Ruby: Dynamically defining classes based on user inputRuby：根据用户输入动态定义类
【发布时间】：2011-07-04 16:21:11
【问题描述】：

我正在用 Ruby 创建一个库，允许用户访问外部 API。可以通过 SOAP 或 REST API 访问该 API。我想支持两者。

我首先在不同的模块中定义了必要的对象。例如：

soap_connecton = Library::Soap::Connection.new(username, password)
response = soap_connection.create Library::Soap::LibraryObject.new(type, data, etc)
puts response.class # Library::Soap::Response

rest_connecton = Library::Rest::Connection.new(username, password)
response = rest_connection.create Library::Rest::LibraryObject.new(type, data, etc)
puts response.class # Library::Rest::Response

我想做的是允许用户指定他们只希望使用其中一个 API，可能是这样的：

Library::Modes.set_mode(Library::Modes::Rest)
rest_connection = Library::Connection.new(username, password)
response = rest_connection.create Library::LibraryObject.new(type, data, etc)
puts response.class # Library::Response

但是，我还没有找到一种方法来动态设置，例如，基于Library::Modes.set_mode 的输入，Library::Connection。实现此功能的最佳方式是什么？

【问题讨论】：

标签： ruby class dynamic

【解决方案1】：

墨菲定律盛行；将问题发布到 Stack Overflow 后立即找到答案。

这段代码似乎对我有用：

module Library
  class Modes
    Rest = 1
    Soap = 2

    def self.set_mode(mode)
      case mode
      when Rest
        Library.const_set "Connection", Class.new(Library::Rest::Connection)
        Library.const_set "LibraryObject", Class.new(Library::Rest::LibraryObject)
      when Soap
        Library.const_set "Connection", Class.new(Library::Soap::Connection)
        Library.const_set "LibraryObject", Class.new(Library::Soap::LibraryObject)
      else
        throw "#{mode.to_s} is not a valid Library::Mode"
      end
    end
  end
end

快速测试：

Library::Modes.set_mode(Library::Modes::Rest)
puts Library::Connection.class == Library::Rest::Connection.class # true
c = Library::Connection.new(username, password)

【讨论】：