Mega Code Archive
Undo by a Command
<![CDATA[
class Command
attr_reader :description
def initialize(description)
@description = description
end
def execute
end
end
class CreateFile < Command
def initialize(path, contents)
super "Create file: #{path}"
@path = path
@contents = contents
end
def execute
f = File.open(@path, "w")
f.write(@contents)
f.close
end
def unexecute
File.delete(@path)
end
end
class DeleteFile < Command
def initialize(path)
super "Delete file: #{path}"
@path = path
end
def execute
if File.exists?(@path)
@contents = File.read(@path)
end
f = File.delete(@path)
end
def unexecute
if @contents
f = File.open(@path,"w")
f.write(@contents)
f.close
end
end
end
class CopyFile < Command
def initialize(source, target)
super("Copy file: #{source} to #{target}")
@source = source
@target = target
end
def execute
puts @source + ">>" + @target
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 description
description = ''
@commands.each {|cmd| description += cmd.description + "\n"}
description
end
def unexecute
@commands.reverse.each { |cmd| cmd.unexecute }
end
end
cmds = CompositeCommand.new
cmds.add_command(CreateFile.new('file1.txt', "hello world\n"))
cmds.add_command(CopyFile.new('file1.txt', 'file2.txt'))
cmds.add_command(DeleteFile.new('file1.txt'))
cmds.execute
puts(cmds.description)
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