in reply to DBI placeholders for spatial data
Have you tried passing a whole point-string for each placeholder?
So something like:
$arg =' POINT ( -4.67682813534559 58.3335955352018 ) ' -- then using execute($arg) for a statement with ST_GeomFromText( ? ) -- -- (maybe casting the argument to WKT, if such casting is supported)
(just curious, it probably won't work either...)