On Jan 21, 2008 8:34 AM, Ted Zlatanov <[EMAIL PROTECTED]> wrote:
> I have some existing RDBO classes, all inheriting from a common
> BaseObject parent. If I want some of them to be selectively cached,
> currently I have to create a BaseObject::Cached that inherits from
> RDBO::Cached (I do this with a copy+edit, see below), and then each of
> my classes can inherit from the cached variation. The issue is that any
> functionality in BaseObject will not be in my cached variation unless I
> do a copy+edit. I considered making BaseObject::Cached inherit from
> BaseObject and RDBO::Cached but that seems like asking for trouble.
I do this, and so far the world has not ended :)
package MyCorp::DB::Object::Cached;
use base 'Rose::DB::Object::Cached';
...
package MyProj::DB::Object;
use base 'MyCorp::DB::Object';
...
package MyProj::DB::Object::Cached;
use base qw(MyCorp::DB::Object::Cached MyProj::DB::Object);
Obviously this doesn't allow methods in MyProj::DB::Object::Cached to
override methods in MyCorp::DB::Object::Cached, but every arrangement
has some tradeoff, thanks to Perl's left-most depth-first dispatch.
(To get a better arrangement, you can always use Class::C3 or
something...)
> Is there an easier way? If a mixin could do it that would be great. I
> didn't see a way in the docs. If not, maybe there's a better approach
> I'm missing.
When I need a mix-in, I just "make one" by manually importing methods
as needed. Writing a helper for this isn't too hard. Look around
line 560 of this file for an example:
http://search.cpan.org/src/JSIRACUSA/Rose-HTML-Objects-0.552/lib/Rose/HTML/Object.pm
IMO, all such things are fair in super-wide-usage base classes. Do
the complicated stuff in a very few well-defined places and reap the
benefits broadly.
-John
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