Yes, I could do that all in BUILDARGS, but "look at how tedious that is", when compared with doing the stuff as (fake) accessors. In a way this feels to me like Java where every data structure has to become a class.

The following is a helper (role) that merely ingests either a premade dbh, or otherwise, a db username, db password and a DSN, to use DBI to make the DBH from:

package Moo::Role::DBIConnection;
use Moo::Role;
use Filter::signatures;
use feature 'signatures';
no warnings 'experimental::signatures';
use DBI;

our $VERSION = '0.01';

=head1 NAME

Moo::Role::DBIConnection

=head1 SYNOPSIS

    { package My::Example;
      use Moo 2;
      with 'Moo::Role::DBIConnection';
    };

    # Connect using the parameters
    my $writer = My::Example->new(
        dbh => {
            dsn  => '...',
            user => '...',
            password => '...',
            options => '...',
        },
    );

    # ... or alternatively if you have a connection already
    my $writer2 = My::Example->new(
        dbh => $dbh,
    );

=cut

has 'dbh' => (
    is => 'lazy',
    default => \&_connect_db,
);

has 'dsn' => (
    is => 'ro',
);

has 'user' => (
    is => 'ro',
);

has 'password' => (
    is => 'ro',
);

has 'options' => (
    is => 'ro',
);

sub _connect_db( $self ) {
    my $dbh = DBI->connect(
        $self->dsn, $self->user, $self->password, $self->options
    );
}

1;

[download]

Somehow, I think shouldn't have to make the dsn, name and password accessors just so I can use them from _connect_db, and ideally, there would be a nicer thing that implements what the Moo*-supplied ->new() does, except that it expects just a hashref, instead of expecting accessors on $self.

But I haven't seen that yet, so it's not really a feature I'd want to see in Perl 7. If it happens for Perl 7 that would be doubly great, of course!

In reply to Re^5: If Perl 5 were to become Perl 7, what (backward-compatible) features would you want to see? by Corion
in thread If Perl 5 were to become Perl 7, what (backward-compatible) features would you want to see? by haukex

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