Pixie and Tangram implement Prevalyer-style persistence without the
deficiency you speak of.
I strongly recommend that you take a good, long, hard look at Pixie.
Figure out if you really need to have the logic that drives your
object's getters, setters, etc bound to your persistence mechanism.
Otherwise, if you do want to keep them bound, there are some very well
established systems for modelling such systems - Alzabo would be well
worth a look.
This wheel has been re-invented far too many times already.
Sam.
On Mon, 09 Feb 2004 21:23, Graciliano M. P. wrote;
> I have just released Class::HPLOO 0.11, with support for attributes
> definitions.
>
> I have inserted the attribute support to build an automatically object
> persistence system for OODB through Class::HPLOO.
>
> First, some example of the new syntax for attributes:
>
> use Class::HPLOO ;
>
> class User {
>
> attr( str name , int age , &my_word_type user , &my_word_type pass ,
array
> links ) ;
>
> ## my personalized type:
> sub my_word_type ($value) {
> $value =~ s/\W//gs ;
> $value = lc($value) ;
> return $value ;
> }
>
> ## initializer for the object:
> sub User ( $name , $age , $user , $pass , @links ) {
> ## through set method:
> $this->set_name($name) ;
> $this->set_links(@links) ;
>
> ## through tied key:
> $this->{age} = $age ;
> $this->{user} = $user ;
> $this->{pass} = $pass ;
> }
>
> ## some method:
> sub dump_user {
> print "USER: $this->{user}\n" ;
> print " name: $this->{name}\n" ;
> print " age: $this->{age}\n" ;
> print " links: ". join(" ", $this->get_links) ."\n" ;
> print "\n" ;
> }
>
> }
>
> ## USAGE:
> package main ;
>
> my $user = new User( 'Joe' , '30' , 'JOE' , 1234 , 'www.perl.com' ,
> 'www.cpan.org' ) ;
> $user->dump_user ;
>
> exit;
>
>
> The idea of the attributes, is to give a type to them and the setter
and
> getter methods. Soo, with a method to access or set the attributes we
can
> know when they are changed or not, soo will be possible to define if an
> object is "dirty" or "clean", needed to make the persistent proxy
system.
>
> The DB communication will be made through HDB (a module that I haven't
> released yet, for now it's just for our internal use in our projects,
but
> will be there for the public). With HDB we don't use SQL, or don't need
to
> use, to work with the DB, we just use commands and syntax based in Perl
it
> self. Soo, we can work with any type of DB without need to care with
the
> nuances of each SQL or behavior of each DB type. Soo, the persistence
system
> will work in any DB, from SQLIte to MySQL and Oracle.
>
> But the seconde idea, is to make an easy and simple way to create a
> persistence class. For example, in Java the easier framework for
persistence
> is the "Prevayler" system (not made by SUN), where we just declare the
clas
> with that:
>
> public class User implements Serializable {
> ...
> }
>
> And bingo, the persistence system is done. But "Prevayler" use a log
> persistence system, soo it doesn't use DB, just a log with all the
commands
> send to an object. Soo, when the system is reloaded, the objects are
rebuild
> with all the commands in the log.
>
> But for a true persistent system, that works in different processes,
> different machines and for big systems, it really need to be made with
a
> true DB.
>
> But how to to make this simple and easy in Perl?
>
> I'm talking about the declaration and syntax definition for that. Since
how
> to build what happens behind the framework is just the easy part,
specially
> with the resources that I have here.
>
> For example, in Perl we don't have the "implements" resource for
classes.
> But with just an "extends" system it won't work too, since the
persistence
> system need to change the setter and getter methods, also inserting
> "mask/layer" classes (proxy) when an object has some association with
other
> object.
>
> But the biggest problem in the definition, is how to just define simple
like
> in the "Prevayler" example, and also define the DB connection?
>
> Soo, before start to work on that, I'm just asking for some opinion
from the
> authors about the persistence system and the new attribute definition.
>
> Thanks in advance.
>
> Regards,
> Graciliano M. P.
>
>
>
>
>
--
Sam Vilain, sam /\T vilain |><>T net, PGP key ID: 0x05B52F13
(include my PGP key ID in personal replies to avoid spam filtering)
I never loved another person the way I loved myself.
MAE WEST
