# File lib/dm-migrations/migration.rb, line 17
    def initialize( position, name, opts = {}, &block )
      @position, @name = position, name
      @options = opts

      @database = DataMapper.repository(@options[:database] || :default)
      @adapter = @database.adapter

      case @adapter.class.to_s
      when /Sqlite3/  then @adapter.extend(SQL::Sqlite3)
      when /Mysql/    then @adapter.extend(SQL::Mysql)
      when /Postgres/ then @adapter.extend(SQL::Postgresql)
      else
        raise "Unsupported Migration Adapter #{@adapter.class}"
      end

      @verbose = @options.has_key?(:verbose) ? @options[:verbose] : true

      @up_action   = lambda {}
      @down_action = lambda {}

      instance_eval &block
    end