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package DBD::Gofer::Policy::Base;
# $Id: Base.pm 10087 2007-10-16 12:42:37Z timbo $
#
# Copyright (c) 2007, Tim Bunce, Ireland
#
# You may distribute under the terms of either the GNU General Public
# License or the Artistic License, as specified in the Perl README file.
use strict;
use warnings;
use Carp;
our $VERSION = sprintf("0.%06d", q$Revision: 10087 $ =~ /(\d+)/o);
our $AUTOLOAD;
my %policy_defaults = (
# force connect method (unless overridden by go_connect_method=>'...' attribute)
# if false: call same method on client as on server
connect_method => 'connect',
# force prepare method (unless overridden by go_prepare_method=>'...' attribute)
# if false: call same method on client as on server
prepare_method => 'prepare',
skip_connect_check => 0,
skip_default_methods => 0,
skip_prepare_check => 0,
skip_ping => 0,
dbh_attribute_update => 'every',
dbh_attribute_list => ['*'],
locally_quote => 0,
locally_quote_identifier => 0,
cache_parse_trace_flags => 1,
cache_parse_trace_flag => 1,
cache_data_sources => 1,
cache_type_info_all => 1,
cache_tables => 0,
cache_table_info => 0,
cache_column_info => 0,
cache_primary_key_info => 0,
cache_foreign_key_info => 0,
cache_statistics_info => 0,
cache_get_info => 0,
cache_func => 0,
);
my $base_policy_file = $INC{"DBD/Gofer/Policy/Base.pm"};
__PACKAGE__->create_policy_subs(\%policy_defaults);
sub create_policy_subs {
my ($class, $policy_defaults) = @_;
while ( my ($policy_name, $policy_default) = each %$policy_defaults) {
my $policy_attr_name = "go_$policy_name";
my $sub = sub {
# $policy->foo($attr, ...)
#carp "$policy_name($_[1],...)";
# return the policy default value unless an attribute overrides it
return (ref $_[1] && exists $_[1]->{$policy_attr_name})
? $_[1]->{$policy_attr_name}
: $policy_default;
};
no strict 'refs';
*{$class . '::' . $policy_name} = $sub;
}
}
sub AUTOLOAD {
carp "Unknown policy name $AUTOLOAD used";
# only warn once
no strict 'refs';
*$AUTOLOAD = sub { undef };
return undef;
}
sub new {
my ($class, $args) = @_;
my $policy = {};
bless $policy, $class;
}
sub DESTROY { };
1;
=head1 NAME
DBD::Gofer::Policy::Base - Base class for DBD::Gofer policies
=head1 SYNOPSIS
$dbh = DBI->connect("dbi:Gofer:transport=...;policy=...", ...)
=head1 DESCRIPTION
DBD::Gofer can be configured via a 'policy' mechanism that allows you to
fine-tune the number of round-trips to the Gofer server. The policies are
grouped into classes (which may be subclassed) and referenced by the name of
the class.
The L<DBD::Gofer::Policy::Base> class is the base class for all the policy
classes and describes all the individual policy items.
The Base policy is not used directly. You should use a policy class derived from it.
=head1 POLICY CLASSES
Three policy classes are supplied with DBD::Gofer:
L<DBD::Gofer::Policy::pedantic> is most 'transparent' but slowest because it
makes more round-trips to the Gofer server.
L<DBD::Gofer::Policy::classic> is a reasonable compromise - it's the default policy.
L<DBD::Gofer::Policy::rush> is fastest, but may require code changes in your applications.
Generally the default C<classic> policy is fine. When first testing an existing
application with Gofer it is a good idea to start with the C<pedantic> policy
first and then switch to C<classic> or a custom policy, for final testing.
=head1 POLICY ITEMS
These are temporary docs: See the source code for list of policies and their defaults.
In a future version the policies and their defaults will be defined in the pod and parsed out at load-time.
See the source code to this module for more details.
=head1 POLICY CUSTOMIZATION
XXX This area of DBD::Gofer is subject to change.
There are three ways to customize policies:
Policy classes are designed to influence the overall behaviour of DBD::Gofer
with existing, unaltered programs, so they work in a reasonably optimal way
without requiring code changes. You can implement new policy classes as
subclasses of existing policies.
In many cases individual policy items can be overridden on a case-by-case basis
within your application code. You do this by passing a corresponding
C<<go_<policy_name>>> attribute into DBI methods by your application code.
This let's you fine-tune the behaviour for special cases.
The policy items are implemented as methods. In many cases the methods are
passed parameters relating to the DBD::Gofer code being executed. This means
the policy can implement dynamic behaviour that varies depending on the
particular circumstances, such as the particular statement being executed.
=head1 AUTHOR
Tim Bunce, L<http://www.tim.bunce.name>
=head1 LICENCE AND COPYRIGHT
Copyright (c) 2007, Tim Bunce, Ireland. All rights reserved.
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself. See L<perlartistic>.
=cut
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