I think perhaps you want something that ends up looking more like this: 

    has testdir => (
        traits => ['DirOption'],
        isa => 'Str',
        is => 'rw',
        rootdir => '/home/paulatreides',
    );

[download]
You can read the Moose::Manual entry on attribute traits to see how that is accomplished, it is fairly straightforward and common use of attribute traits (to add more options to has).

As for your _build_rootdir approach, you could use MooseX::Role::Parameterized for this. In that case it will look more like this instead 

    has testdir => (
        traits => [ 'DirOption' => { rootdir => '/home/paulatreides' }
+ ],
        isa => 'Str',
        is => 'rw',
    );

[download]
This is a less common way to use attribute traits, but it too should work.

-stvn

In reply to Re: Moose: Where to define a method required by an attribute trait? by stvn
in thread Moose: Where to define a method required by an attribute trait? by maxhq

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