varargs mapping filter_mapping( mapping map, string func, mixed ob, mixed extra )
{
    mixed  *bing;
    mapping ret;
    int     i;

    ret = ([ ]);
    bing = keys( map );
    for( i = 0; i < sizeof( bing ); i++ )
    {
	if( call_other( ob, func, map[ bing[ i ] ], extra ) )
	    ret[ bing[ i ] ] = map[ bing[ i ] ];
    }
    return ret;
}				/* filter_mapping() */