On Sun, Sep 25, 2005 at 08:07:58AM -0700, Dean Arnold wrote: > Tim Bunce wrote: > > I'm interested to hear stories of people who have subclassed the DBI, > > or used modules that subclass the DBI. > > My subclasses (or attempted subclasses): > > DBIx::Chart - worked (tho it took me a few years to get it right ;^) > > DBIx::Threaded - didn't work (tho I managed to deliver a "faux" subclass) > > > Was subclassing the DBI a good approach? > > DBIx::Chart - yes, tho it might have been a bit easier > > DBIx::Threaded - no, tho it could have been useful > but for the magic handle requirement (see below) > > > Where there any problems? > > DBix::Chart - since it was both subclassing, *and* encapsulating/ > aggregating DBI objects, things got a bit confusing as to which > DBI object's methods/members to expose for any given call. Not certain > DBI can do anything about that, tho. > > DBIx::Threaded - the requirement that handles *must* go thru > DBI at some point to acquire "magic" created an insurrmountable > issue (since the handles returned by DBIx::Threaded's needed to be > threadsafe and implement Thread::Queue::Queueable). Its not clear > to me precisely why DBI requires the magic, other than as > "belt and suspenders" security ? (Or maybe to support the > tied object mechanism ?)
Yeap, it's due to DBI handles being tied hashes, and that the inner hash has extra "magic" attached for internal use by the DBI. > And as I suggested a while > ago, if an i/f were provided to "conjure" a handle so it > acquired the needed magic, that might have solved the issue. DBI::_new_handle() or perhaps DBI::_setup_handle() might help, but you're deep in the internals there. Followup on dev-dev if you'd like more info. > Also, being able to capture the driver-specific methods > installed via install_method would be nice to support > same in subclasses such as DBIx::Threaded. Using AUTOLOAD might provide a way around that. > > Could it have been done well/better some other way? > > See comments above wrt magic and installed methods. Thanks Dean. Anyone else have a DBI subclassing story to tell? Tim.
