Share a design patten: Command patten. Migration in Ruby On Rails is a good example of Command patten.
Bellow is code about how to create a Command patten in Ruby.
The code bellow defined CreateFile and CopyFile two classes, use Command patten and Composite patten log requests, and support undoable operations.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 | class Command attr_reader :description def initialize(description) @description = description end def execute end end class CreateFile < Command def initialize(file_name) super("create file: #{file_name}") end def execute puts "creating file" end def unexecute puts "deleting created file" end end class CopyFile < Command def initialize(file_name) super("copy file: #{file_name}") end def execute puts "copying file" end def unexecute puts "deleting copied file" end end class CompositeCommand < Command def initialize @commands = [] end def add_command(cmd) @commands << cmd end def execute @commands.each { |cmd| cmd.execute } end def unexecute @commands.reverse.each { |cmd| cmd.unexecute } end def description description = "" @commands.each { |cmd| description += cmd.description + "\n" } description end end cmds = CompositeCommand.new cmds.add_command(CreateFile.new("file")) cmds.add_command(CopyFile.new("file")) puts "description".ljust(60, "=") puts cmds.description puts "execute".ljust(60, "=") cmds.execute puts "unexecute".ljust(60, "=") cmds.unexecute |
