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Re^2: Python OO v Moose

by Ea (Hermit)
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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[Corion]: marto: Yeah - their mother picked all three of them up at the kindergarden to then go to the hospital, and all three of them were well behaved, and all also were quite obedient when they came home, so they recognized the situation
[Corion]: Nice to see that the kids have some understanding of important things that happen and the appropriate behaviour :)
[marto]: at times mine surprise me with this behavior :)

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