Re: Extract SQL-Engine basics from DBD::File

On Thu, May 27, 2010 at 01:05:05PM +0200, H.Merijn Brand wrote:
> On Thu, 27 May 2010 09:53:02 +0000, Jens Rehsack
> <[email protected]> wrote:
> 
> > Hi developers,
> > 
> > during refactoring of DBD::File and new wishes (e.g. SQL_IDENTIFIER_CASE
> > from Martin Evans, getinfo() support, ...) and my own try of a pure-perl
> > DBD for system tables (DBD::Sys) I see many common code.
> > 
> > I would like to extract the common code into a base class DBD - maybe
> > named DBD::SQLPerl (placed SQL in from for private methods and attributes
> > naming - the should have the prefix "sql_").
> > 
> > I know at least two additional DBD's which could benefit from that:
> > - DBD::Google from Darren Chamberlain (I don't know if he is subscribed
> >    to [email protected])
> > - DBD::Sys from me
> > 
> > If there are more, it would be great to know about them.
> 
> I do have no objections to refactoring common code into a new module.
> I've got no opinion (yet) for the name(space) of that module.
> 
> What I would like to see though, before we end up in quicksand, is to
> first `finish' the f_meta work, so DBI would at least be releasable
> again. Call me conservative, but that would make me happy.

Agreed. Let's work towards a stable 1.612 release first.

On Thu, May 27, 2010 at 12:01:39PM +0000, Jens Rehsack wrote:
> 
> >What I would like to see though, before we end up in quicksand, is to
> >first `finish' the f_meta work, so DBI would at least be releasable
> >again. Call me conservative, but that would make me happy.
> 
> Sure, but I would favour a development release over a real release.

To that end, I've just uploaded DBI-1.611_90.

(Also, can https://rt.cpan.org/Public/Bug/Display.html?id=56561
be closed?)

> I want to add some more test (DBD::File, DBD::DBM) and some documentation
> how to implement DBD'S based on DBD::File as well as new DBD::SQLPerl.
> 
> And I'd like to add a link to http://dbi.perl.org/support/ (section:
> "CREATING A NEW DRIVER").

That's great. Thanks. I'd like to make a release sometime next week.

On Thu, May 27, 2010 at 12:35:59PM -0700, Darren Duncan wrote:
> 
> I had already been thinking of this need for awhile, but in that
> context it would have been a utility module, say with "common" in
> its name or something.
> 
> Unless there is already a precedent otherwise, I recommend leaving
> the DBD::* namespace for actual DBI drivers, and utilities go in
> some other namespace, though perhaps DBD::Util::* or something.

I'd like to keep the DBD::* namespace reserved for actual drivers.
The DBI::DBD* and DBI::DBD::* namespaces would be suitable.
Perhaps DBI::DBD::PerlBase (for 'perl base class').

> The choice may also be affected by whether the new module is meant
> to be subclassed by a DBI module or just "used" ... the latter makes
> more sense if it would be used by multiple component classes like
> the driver and statement handles, unless the utility has one for
> each of those, but I wouldn't make it a subclassing situation.

Certainly the import/mixin vs subclass aspect of the design needs
some exploration. There might be a role for both a DBI::DBD::PerlBase
class plus a DBI::DBD::Utilities module.

Tim.