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Postings from July 2008
How about this:
has 'min' => (
is => 'rw',
isa => 'Int',
default => sub { NEGATIVE_INFINITY },
trigger => sub {
my ( $self, $val ) = @_;
carp "min is > max" unless $val <= $self->max;
}
);
has 'max' => (
is => 'rw',
isa => 'Int',
default => sub { POSITIVE_INFINITY },
trigger => sub {
my ( $self, $val ) = @_;
carp "max is < min" unless $val >= $self->min;
}
);
No BUILD needed. Consistency checked by the triggers whenever min and
max are set...
Besides defining negative and positive infinity, the only problem I
see is if both min and max are set at the same time, as in the
constructor. I don't know which error you'd get if the object was
initialized like this:
my $foo = Foo->new(
min => 1,
max => -1,
);
Charles Alderman
----- Original Message -----
From: Guillaume Rousse <Guillaume.Rousse@inria.fr>
Sent: Mon, 14 Jul 2008 23:15:49 +0200
Re: checking consistency between attributes
> Hello list.
>
> What's the best way to check consistency between attributes values ? Is
> there anything better than a dedicated BUILD method, such as:
>
> use Moose;
> use Carp;
>
> has 'min' => (is => 'rw', isa => 'Int');
> has 'max' => (is => 'rw', isa => 'Int');
>
> sub BUILD {
> my ($self, $params) = @_;
>
> my ($max, $min) = ($self->max(), $self->min());
> croak "max < min" if defined $max && defined $min && $max < $min;
> }
> --
> Guillaume Rousse
> Moyens Informatiques - INRIA Futurs
> Tel: 01 69 35 69 62
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