def adapter(type)
      begin
        @_adapter = XapianDb::Adapters.const_get("#{camelize(type.to_s)}Adapter")
      rescue NameError
        require File.dirname(__FILE__) + "/adapters/#{type}_adapter"
        @_adapter = XapianDb::Adapters.const_get("#{camelize(type.to_s)}Adapter")
      end
    end
def adapter(type)
      begin
        @_adapter = XapianDb::Adapters.const_get("#{camelize(type.to_s)}Adapter")
      rescue NameError
        require File.dirname(__FILE__) + "/adapters/#{type}_adapter"
        @_adapter = XapianDb::Adapters.const_get("#{camelize(type.to_s)}Adapter")
      end
    end
Set the adapter
 @param [Symbol] type The adapter type; the following adapters are available:
   - :generic ({XapianDb::Adapters::GenericAdapter})
   - :active_record ({XapianDb::Adapters::ActiveRecordAdapter})
   - :datamapper ({XapianDb::Adapters::DatamapperAdapter})