register particular method used as command

scratch.rb

#!/usr/bin/env ruby

module Kernel
  private
  def this_method
   caller[0][/`([^']*)'/, 1]
  end

  def calling_method
   caller[1][/`([^']*)'/, 1]
  end
end

class Command
  @@command = []
  def self.command_list; @@command end

  def register
    meth = calling_method
    @@command << meth unless @@command.include? meth
  end

  def registerd?(methname)
    @@command.include? methname
  end

  def meth1; register; "meth1" end
  def meth2; register; "meth2" end
end

Command.new.meth1     # => "meth1"
Command.new.meth2     # => "meth2"
Command.command_list  # => ["meth1", "meth2"]

class Command2
  @@command = []
  class << self
    def method_added(name)
        @@command << name if name.to_s =~ /^cmd_/
    end
    def command_list; @@command end
  end

  def meth1; "meth1" end
  def meth2; "meth2" end

  def cmd_meth1; "cmd_meth1" end
  alias_method :cmd_meth2, :meth2
end

Command2.new.meth1     # => "meth1"
Command2.new.meth2     # => "meth2"
Command2.command_list  # => [:cmd_meth1, :cmd_meth2]

class Command3
  @@command = []
  class << self
    def command_methods(*meth)
      @@command.concat meth
    end
    def command_list; @@command end
  end

  def meth1; "meth1" end
  def meth2; "meth2" end
  def meth3; "meth3" end
  command_methods :meth1, :meth2
end

Command3.new.meth1     # => "meth1"
Command3.new.meth2     # => "meth2"
Command3.command_list  # => [:meth1, :meth2]