Simon Slavin wrote:
> How do you pass the handle from your C code to your Tcl code ?
I don't. I pass it from Tcl to C.
The handle in Tcl is a command name registered with the interpreter.
SQLite attaches a structure to the registration that contains the
underlying handle as used by the C API.
I'm writing a Tcl extension in C and I don't want to touch a bunch of
Tcl code. The Tcl caller gives me its command-name handle to the DB.
I ask the Tcl core for the registration data for that command name, and
use it to get the underlying SQLite handle for my C calls.
(Checking whether I've got a real Tcl db handle is not 100% fool proof,
but takes care of basic caller stupidity and is good enough for my
app.)
With error checks removed:
Tcl_CmdInfo cmdInfo;
const char* zDbHandle = Tcl_GetStringFromObj(objv[2], 0);
Tcl_GetCommandInfo(pInterp, zDbHandle, &cmdInfo);
sqlite3 *pDb = *((sqlite3**)cmdInfo.objClientData);
/* Carry on, using pDb in C API calls.
*/
I was considering asking about this a while ago on this group, but opted
not to for fear of being publicly flogged by drh. :)
Actually, I was hoping the SQLite devs would promise not to change the
way they do Tcl command registration in future releases, so this kind
of thing will continue to work.
> You are sharing the same connection to the database between the two
> languages, right ?
Yep.
> You're not doing your INSERTs from one connection and your COMMITs from
> another ?
Right, the one connection is shared.
Eric
--
Eric A. Smith
Substitute "damn" every time you're inclined to write "very"; your
editor will delete it and the writing will be just as it should be.
-- Mark Twain
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