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Re^2: Python OO v Moose

by Ea (Friar)
on Feb 07, 2013 at 16:01 UTC ( #1017683=note: print w/ replies, xml ) Need Help??


in reply to Re: Python OO v Moose
in thread Python OO v Moose

That's a little more compact than I was hoping for to show to non-Perl people, but I may start using it myself. <quote>Also I'll offer a MooX::Struct example for your class. MooX::Struct is a compact builder for simple classes that mainly consist of attributes (not methods).</quote> I was looking for this just last week, but I wanted one of the attributes to be a unique list, so there was a bit of overhead in writing the accessors.

has 'name' => ( is => 'rw', isa => 'Str', required => 1 ); has 'members' => ( is => 'rw', isa => 'HashRef', default => sub{ {} }, ); sub add_members { my ($self, @members) = @_; $self->members()->{$_}++ for (@members); # no duplicates in list } sub list_members { my $self = shift; return keys %{$self->members()}; }
I use it to create a group with a name and then add members to the list as I pick them out of a database. When I'm finished in the database, I go through all the groups and dump the members list. How would you do that in MooX::Struct and would it be able to modify the members list after instantiation?

Sometimes I can think of 6 impossible LDAP attributes before breakfast.


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Re^3: Python OO v Moose
by tobyink (Abbot) on Feb 07, 2013 at 16:43 UTC

    By default, all attributes in MooX::Struct are read-only, but it's easy to make them read-write...

    use MooX::Struct -rw, Person => [qw( $name @addresses )];

    For your members example, Moose's native traits would probably be helpful. Moo doesn't currently offer anything similar to this, but there is somebody developing such a beast - I believe it will be on CPAN soonish. I'd probably do something along these lines...

    use v5.14; package Person { use Moose; use overload q[""] => sub { $_[0]->name }, fallback => 1; has name => ( is => 'ro', isa => 'Str', required => 1, ); } package Club { use Moose; use overload q[""] => sub { $_[0]->name }, fallback => 1; has name => ( is => 'ro', isa => 'Str', required => 1, ); # This is a private attribute. We want people to only # manipulate the member list via add_members, etc. has _members => ( traits => ['Array'], is => 'ro', isa => 'ArrayRef[Person]', init_arg => undef, default => sub { [] }, handles => { add_members => 'push', has_members => 'count', list_members => 'elements', _uniq_members => 'uniq', }, ); # ensure uniqueness after add_members => sub { my $self = shift; @{ $self->_members } = $self->_uniq_members; }; } my $club = Club->new(name => "The Breakfast Club"); $club->add_members( Person->new(name => "Allison"), Person->new(name => "Andy"), Person->new(name => "Brian"), Person->new(name => "Brian"), # duplicate ); $club->add_members( Person->new(name => "Andy"), # duplicate Person->new(name => "Claire"), Person->new(name => "John"), ); say for $club->list_members;
    package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

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