Karen, thanks for the advice!
Let me see if I can get unconfused:
I don't want to pass a type parameter to the role - I want it to
construct it! This is why I have a builder.
I'd really like it to construct $type on its own, based on package
name. What's the best way to do that? Or should I just quit being
cute and do something like
with Role => {child => __PACKAGE__};
Come to think of it, it really isn't so bad. :-) Still, I am curious
to understand if parameterized roles will support a real builder and
how to achieve it.
On Apr 22, 2010, at 4:49 PM, Karen Etheridge wrote:
You are getting an error because the role is attempting to create an
attribute that doesn't exist, because you don't pass a type
parameter to
the role. You should mark that parameter as required, or check that
it
exists first, e.g. one of:
parameter 'type' =>(
isa => 'Str',
required => 1,
builder => '_type',
);
or:
if (my $type = $p->type)
{
has $type =>(is => 'rw');
}
You could also use a default instead of a builder:
parameter 'type' =>(
isa => 'Str',
default => 'human',
);
The error message certainly isn't clear, and it suggests that the
parameter
object does not exist at all in the parameterized role when you do
not pass
a parameter (which does not parallel normal Moose behaviour -- an
attribute
metaobject always exists on the object, even if one constructs an
object
with no values).
On Thu, Apr 22, 2010 at 04:31:20PM -0700, Kate Yoak wrote:
Here is the most straightforward approach that fails with the error
above (the error occurs while trying to use Me):
package Role;
use MooseX::Role::Parameterized;
sub _type{ 'human'; }
parameter 'type' =>(
isa => 'Str',
required => 0,
builder => '_type',
);
role{
my $p = shift;
my $type = $p->type;
has $type =>(is => 'rw');
};
1;
package Me;
use Moose;
with 'Role' => { };
1;
--
New and stirring things are belittled because if they
are not belittled, the humiliating question arises,
"Why then are you not taking part in them?" - H.G.Wells
. . . . .
Karen Etheridge, ka...@etheridge.ca GCS C+++$ USL+++$ P+++$
w--- M++
http://etheridge.ca/ PS++ PE-- b++ DI++++ e++ h
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