class change_key:
    """ Generates a partial SQL command to change a key in a table """

    def __init__( self, key ):
        self.key = key

    def apply_to_table( self, table ):
        """ Changes the key in the table

        :param table: The table to change the key on
        :param type: mygrations.formats.mysql.definitions.table
        """
        table.change_key( self.key )

    def __str__( self ):
        return 'DROP KEY `%s`, ADD %s' % ( self.key.name, str( self.key ) )
