WHAT IS DSL USED FOR?

配置文件用来做什么？

存数据 & 取数据

So, what is DSL?

实例 1 解决方案

???

传统解决方案

DSL FOR DSL解决方案

                    class Gemfile::Configuration
  include Qor::Dsl
  default_configs [ENV['BUNDLE_GEMFILE'], 'Gemfile']

  node :gem

  [:git, :path, :group].map do |name|
    node name do
      node :gem
    end
  end
end
              

查询数据（1）

                        # 找到第一个节点
first_node = Gemfile::Configuration.first('gem')
#=> #<Qor::Dsl::Node:0x3fb8 {name: "rails", config: :gem}>

first_node.name
#=> rails

first_node.options
#=> {git: "git://github.com/rails/rails.git"}

# 找到第一个path节点对象
first_path = Gemfile::Configuration.first('path')
#=> <Qor::Dsl::Node:0x3fd2100 {name: "~/Develop/qor_dsl", config: :path}>

# 嵌套查找
qor_dsl = first_path.first('gem', 'qor_dsl')
#=> <Qor::Dsl::Node:0x3fe4894dc288 {name: "qor_dsl", parent: "{path: ~/Develop/qor_dsl}", config: :gem}>

            

查询数据（2）

                        # 查找父节点
qor_dsl.parent
#=> <Qor::Dsl::Node:0x3fd2100 {name: "~/Develop/qor_dsl", config: :path}>

# 取出children
first_path.children
#=> [<Qor::Dsl::Node:0x3fd2100 {name: "~/Develop/qor_dsl", config: :path}>]

# 取出第一级的Gems
Gemfile::Configuration.find('gem').map(&:name)
#=> ["rails", "capistrano-confirm", "paygent"]

Gemfile::Configuration.find('gem')[-1].name
#=> paygent

            

查询数据（3）

                        # 所有级别的Gems
Gemfile::Configuration.deep_find('gem').map(&:name)
#=> ["rails", "capistrano-confirm", "paygent", "qor_dsl", "activesupport", "actionpack", "pry-rails", "timecop"]


# 取出所有Development环境下的Gem
Gemfile::Configuration.deep_find('gem') do |node|
  parent = node.parent
  parent.root? ||
    !parent.is_node?(:group) ||
    parent.is_node?(:group, :development)
end.map(&:name)
#=> ["rails", "capistrano-confirm", "paygent", "qor_dsl", "activesupport", "actionpack", "pry-rails"]

            

实例 2 解决方案

???

传统解决方案

DSL FOR DSL解决方案

                        class Nagios::Configuration
  include Qor::Dsl
  node :contact_emails

  node :mail do
    node :address
  end

  node :server do
    node :contact_emails, inherit: true
    node :host
    node :port, default_value: 22
    node :username, default_value: 'app'

    node :check_disk, default_options: {warning: '10%', critical: '8%'}
    node :check_load
    node :check_memcached
    node :check_mysql_slave
  end
end
              

查询数据

                        # 继承父级
Nagios::Configuration.first('server', 'server1').first(:contact_emails).value
#=> "[email protected]"

# 重写继承
Nagios::Configuration.first('server', 'server2').first(:contact_emails).value
#=> [email protected]

# 默认值
Nagios::Configuration.first('server', 'server1').first(:port).value
#=> 22

Nagios::Configuration.first('server', 'server1').first(:check_disk).options
#=> {warning: '10%', critical: '8%'}

            

实例1，实例2传统解决方案总结

简单？

枯燥 && 乏味 && 重复

Don't Repeat Yourself！

DSL FOR DSL

Meta Programming?

Writing Code That Writes Code

幕后英雄 - Qor DSL

如何使用

API

            = Class methods:
first
find
deep_find

default_configs
load

= Instance methods:
name
options
default_options
value
default_value
block
default_block

parent
children
root
root?
dummy?
is_node?

            

Qor DSL可用来做什么？

Sinatra的样例

require 'sinatra'

get '/hi' do
  "Hello World!"
end

            

Qor DSL & Rack的实现

# 代码实现
require 'qor_dsl'

class SimpleWeb
  include Qor::Dsl
  node :get
end

run proc { |env| [200, {'Content-Type' => 'text'}, [SimpleWeb.first(:get, env["PATH_INFO"]).block.call]] }

# 路由
SimpleWeb.load do
  get '/hi' do
    'Hello world!'
  end
end

            

稍复杂一点

get '/hi' do
  "Hello #{env["PATH_INFO"]}"
end

            

class SimpleWeb
  class Configuration
    include Qor::Dsl
    node :get
  end

  class Request
    attr_accessor :env

    def initialize env
      self.env = env
    end

    def body
      instance_eval(&SimpleWeb::Configuration.first(:get, env["PATH_INFO"]).block)
    end

    def call
      [200, {'Content-Type' => 'text'}, [body]]
    end
  end
end

run proc { |env| SimpleWeb::Request.new(env).call }

            

再复杂一点

class Available
  def initialize(url, option)
    @url, @option = url, option
  end

  def match(url)
    (@url == url) &&
      (@option[:from]..@option[:to]).include?(Time.now.hour)
  end
end

get %r(/hello/(.*)) do
  "Hello World!"
end

get Available.new("/now", from: 6, to: 18) do
  "Day Time!"
end

get "/now" do
  "Night Time!"
end

            

class SimpleWeb
  class Request
    attr_accessor :env

    def initialize env
      self.env = env
    end

    def route
      SimpleWeb::Configuration.first(:get) do |n|
        name, path = n.name, env["PATH_INFO"]
        name.respond_to?(:match) ? name.match(path) : name == path
      end
    end

    def body
      instance_eval(&route.block)
    end

    def call
      [200, {'Content-Type' => 'text'}, [body]]
    end
  end
end

run proc { |env| SimpleWeb::Request.new(env).call }

            

更幕后英雄
Qor Open Development Platform

如何使用