Oryx::MetaClass - abstract base class for all Oryx meta types

Oryx documentation Contained in the Oryx distribution.

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NAME

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Oryx::MetaClass - abstract base class for all Oryx meta types

INTERFACE

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All Oryx components implement the interface defined herein. This is the basis for all Oryx components to share a common interface. All this really means is that when an object is created, retrieved, deleted etc. then each meta-instance (Oryx::Attribute, Oryx::Association etc.) associated with the class or instance can decide what it wants to do during each call. So when we say:

    CMS::Page->create({ ... });

then in the create() method inherited from Oryx::Class we do something similar to:

    sub create {
        my ($class, $params) = @_;

        # do a few things with $params, exactly what would depend
        # on whether we're using DBI or DBM back-end

        $_->create($query, $params, ...) foreach $class->members;

        # return a newly created instance
    }

Here the members method (defined in Oryx::Class returns all meta-instances hanging off the class, and to each on is the create method delegated; hence the common interface.

create

meta object's create() hook

retrieve

meta object's retrieve() hook

update

meta object's update() hook

delete

meta object's delete() hook

meta object's search() hook

construct

meta object's construct() hook

META-DATA ACCESS

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Each meta-type (with the exception of Oryx::Value types) has meta-data associated with it which is usually defined in the $schema class variable used in your persistent classes.

The following are accessors for this meta-data:

meta

usually returns a hash reference which corresponds to the meta-data described in $schema.

getMetaAttribute( $name )

get a value from the meta-data hash ref keyed by $name

setMetaAttribute( $name, $value )

set a value from the meta-data hash ref keyed by $name

SEE ALSO

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Oryx, Oryx::Class

AUTHOR

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Copyright (C) 2005 Richard Hundt <richard NO SPAM AT protea-systems.com>

LICENSE

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This library is free software and may be used under the same terms as Perl itself.

Oryx documentation Contained in the Oryx distribution. 
package Oryx::MetaClass;

# okay, so it's not really a meta-class in the true sense since it
# doesn't get instantiated. Instead, it gets subclassed, but we use
# inheritable class data to achieve the same effect. This is 
# because we're not trying to create our own meta-model so much as
# trying to squeeze a relational data model into Perl's in-built
# meta-model.  Subclassing this via Perl's inheritance mechanism
# preserves class state as if the sub class were a Class instance of a
# MetaClass (which it is, just not this one... Perl's). There is
# meta-data associated with the class which is in the form of a DOM
# Node which was used to define the schema in the first place (and
# which is passed into the constructor of whichever entity derives
# from this class).

use Carp qw(carp croak cluck);
use base qw(Class::Data::Inheritable);

__PACKAGE__->mk_classdata("storage");
__PACKAGE__->mk_classdata("schema");


sub create    { }
sub retrieve  { }
sub update    { }
sub delete    { }
sub search    { }
sub construct { }

sub meta {
    my $class = shift;
    $class->{meta} = shift if @_;
    $class->{meta};
}

sub setMetaAttribute {
    my ($class, $key, $value) = @_;
    $class->meta->{$key} = $value;
}

sub getMetaAttribute {
    my ($class, $key) = @_;
    unless ($class->meta) {
	cluck("$class has no meta");
    }
    return $class->meta->{$key};
}

sub _carp {
    my $thing = ref($_[0]) ? ref($_[0]) : $_[0];
    carp("[$thing] $_[1]");
}

sub _croak {
    my $thing = ref($_[0]) ? ref($_[0]) : $_[0];
    croak("[$thing] $_[1]");
}

1;