Tim Bunce wrote:
On Mon, Jul 28, 2008 at 05:09:03PM +0100, Martin Evans wrote:
Tim Bunce wrote:
On Mon, Jul 28, 2008 at 01:13:50PM +0100, Martin Evans wrote:
Hi,
From the DBI::DBD docs in "The dbd_db_login6 method" I read:
=====
Here’s how you fetch them; as an example we use hostname attribute,
which can be up to 12 characters long excluding null terminator:
SV** svp;
STRLEN len;
char* hostname;
if ( (svp = DBD_ATTRIB_GET_SVP(attr, "drv_hostname", 12)) && SvTRUE(*svp)) {
hostname = SvPV(*svp, len);
DBD__ATTRIB_DELETE(attr, "drv_hostname", 12); /* avoid later STORE */
} else {
hostname = "localhost";
}
=====
My question concerns the comment saying "avoid later STORE". If I have a
DBD::ODBC specific attribute which a) may be specified on the connect
call and b) is copied to any statement handles when they are created and
c) may also be on a statement handle, should I be calling
DBD__ATTRIB_DELETE? and what does that "avoid later STORE" really mean?
After $drh->connect(..., $attr) returns a handle DBI->connect(...)
effectively does $dbh->STORE($_, $attr->{$_}) for keys %$attr;
If the handle has already dealt with the attribute during the drivers
connect/login processing then the later STORE by the DBI is at best
redundant and could, at worse, cause problems/errors/whatever.
So the driver can delete from %$attr any attributes it doesn't want the
DBI to call STORE on later.
Tim.
p.s. patch to DBI::DBD docs most welcome!
Thanks for the clarification.
First patch appears to be:
DBD__ATTRIB_DELETE => DBD_ATTRIB_DELETE
as I can find the latter and not the former. Unless I've got something else
wrong I get a segfault the minute I used DBD_ATTRIB_DELETE and I notice
DBD::Oracle does not use it. Is anyone using DBD_ATTRIB_DELETE and can
confirm it works?
Ah. Bug. It's missing an SvRV. Fixed in r11605. Thanks!
Meanwhile, just use
hv_delete((HV*)SvRV(attribs), key, key_len, G_DISCARD)
instead.
Tim.
Thanks - tis good to be the first ;-)
The replacement call works fine.
I will formulate a patch for the docs and send tomorrow which I'm
presuming will need to include the name fix for DBD_ATTRIB_DELETE as
I've not seen a checkin for that but I have seen a checkin for the above
fix.
BTW, I am aware I /owe/ you a patch for the DBI::DBD docs for tracing
flags but I was way too busy at the time; it is still on my list and I
hope to address that too this week.
Martin
