Maybe you should start with what you want to achieve in the end.

If y always depends on x, don't make it an attribute, but rather a method that calculates the value of y.

If you want to make it a default, use Moose's default facility: 

use Moose;

has 'y' => (
    is => 'Num',
    is => 'rw'
);

has 'x' => (
    is => 'Num',
    is => 'rw',
    default => sub { sqrt(shift->x) },
);

[download]

I'm not a Moose specialist, but I guess that one reason the code does not do what you want is that you try to call methods on objects that haven't been constructed yet.

I also don't see why you want to call a derived BUILD method before the parent BUILD method. Just let the parent construct the parent part of the object, and then do whatever you want in the child.

Perl 6 - second systems done right

In reply to Re: Moose and BUILD by moritz
in thread Moose and BUILD by tj_thompson

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