ruby-on-rails - Ruby - 根据文件名创建一个类？

Question

这是我第一次制作自定义 Rails 生成器，我希望能够根据传递给生成器的参数在模板中创建动态类，但我不知道如何以及如何正确格式化它。

   class Achievements::__FILE__ < Achievement
   end

这是我想要创建的生成类，下面是生成器。另外，我是否在生成器中创建了“成就”目录？

module Achiever
  module Generators
    class AchievementGenerator < Rails::Generators::Base
      source_root File.expand_path('../templates', __FILE__)
      argument :award, :type => :string

      def generate_achievement
        copy_file "achievement.rb", "app/models/achievement/#{file_name}.rb"
      end

      private

      def file_name
        award.underscore
      end

    end
  end
end

Answer 1

使用Module#const_set 。它会自动包含到对象中，因此您可以执行以下操作:

foo.rb

# Defining the class dynamically. Note that it doesn't currently have a name
klass = Class.new do
  attr_accessor(:args)
  def initialize(*args)
    @stuff = args
  end
end
# Getting the class name
class_name = ARGV[0].capitalize
# Assign it to a constant... dynamically. Ruby will give it a name here.
Object.const_set(class_name, klass)
# Create a new instance of it, print the class's name, and print the arguments passed to it. Note: we could just use klass.new, but this is more fun.
my_klass = const_get(class_name).new(ARGV[1..-1])
puts "Created new instance of `" << my_klass.class << "' with arguments: " << my_klass.args.join(", ")

我还没有尝试过这段代码，但它应该会产生类似的结果:

$ ruby foo.rb RubyRules pancakes are better than waffles
Created new instance of `RubyRules' with arguments: pancakes, are, better, than, waffles

此外，const_set 的第一个参数绝对必须以大写字母数字字符开头(就像静态定义常量一样)，否则 Ruby 会产生类似的错误的:

NameError: wrong constant name rubyRules
        --- INSERT STACKTRACE HERE ---