命令组合设计模式 [英] Composite of Commands Design Pattern

问题描述

有没有人在使用复合命令的Ruby中有一个很好的例子？它是一种设计模式混合，我已经看到在各种设计模式文献中提到这听起来相当强大，但还没有找到任何有趣的用例或代码。

解决方案

灵感来自一般想法和这个博客文章中的示例模式实现，这里是一个刺激它可能是什么样的：

  class CompositeCommand 
 def initialize（description，command，undo）
 @ description = description; @命令=命令; @ undo = undo 
 @children = [] 
 end 
 def add_child（child）; @children<<<儿童;自; end 
 def execute 
 @ command.call（）if @command&&& @ command.is_a？（Proc）
 @ children.each {| child | child.execute} 
 end 
 def undo 
 @ children.reverse.each {| child | child.undo} 
 @ undo.call（）if @undo&&& @ undo.is_a？（Proc）
 end 
 end 
  

使用软件安装程序的应用程序：

  class CreateFiles< CompositeCommand 
 def initialize（name）
 cmd = Proc.new {putsOK：＃{name} files created} 
 undo = Proc.new {putsOK：＃{name}文件已删除} 
 super（创建＃{name}文件，cmd，撤消）
 end 
 end 
 
 class SoftwareInstaller 
 def initialize; @命令= []; end 
 def add_command（cmd）; @commands<<< CMD;自;结束
 def install; @ commands.each（安培;：执行）;自;结束
 def卸载; @ commands.reverse.each（安培;：撤消）;自身
 end 
 
安装程序= SoftwareInstaller.new 
 installer.add_command（
 CreateFiles.new（'Binary'）。add_child（
 CreateFiles.new （'Library'））add_child（
 CreateFiles.new（'Executable'）））
 installer.add_command（
 CreateFiles.new（'Settings'）。add_child（
 CreateFiles.new（'Configuration'））add_child（
 CreateFiles.new（'Preferences'））。add_child（
 CreateFiles.new（'Help'）））
 installer.install＃ =>递归运行所有命令
 installer.uninstall 
  

Does anyone have a good example in Ruby of using a Composite of Commands? It is a design pattern hybrid that I have seen mentioned in various Design Patterns literature which sounds quite powerful, but have not been able to find any interesting use cases or code.

解决方案

Inspired by the general idea and the sample pattern implementations in this blog post, here's a stab at what it might look like:

class CompositeCommand
  def initialize(description, command, undo)
    @description=description; @command=command; @undo=undo
    @children = []
  end
  def add_child(child); @children << child; self; end
  def execute
    @command.call() if @command && @command.is_a?(Proc)
    @children.each {|child| child.execute}
  end
  def undo
    @children.reverse.each {|child| child.undo}
    @undo.call() if @undo && @undo.is_a?(Proc)
  end
end

And sample usage using the application of a software installer program:

class CreateFiles < CompositeCommand
  def initialize(name)
    cmd = Proc.new { puts "OK: #{name} files created" }
    undo = Proc.new { puts "OK: #{name} files removed" }
    super("Creating #{name} Files", cmd, undo)
  end
end

class SoftwareInstaller
  def initialize; @commands=[]; end
  def add_command(cmd); @commands << cmd; self; end
  def install; @commands.each(&:execute); self; end
  def uninstall; @commands.reverse.each(&:undo); self end
end

installer = SoftwareInstaller.new
installer.add_command(
  CreateFiles.new('Binary').add_child(
    CreateFiles.new('Library')).add_child(
    CreateFiles.new('Executable')))
installer.add_command(
  CreateFiles.new('Settings').add_child(
    CreateFiles.new('Configuration')).add_child(
    CreateFiles.new('Preferences')).add_child(
    CreateFiles.new('Help')))
installer.install # => Runs all commands recursively
installer.uninstall

这篇关于命令组合设计模式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！