make_immutable, lazy, and 'app'?

Hi all,

I need to stop looking at this.. I have a headache now..

I'm messing around with building a Plack app and had some really odd
behaviour which I tracked back and boiled down to the test cases below.
(unfortunately the result was my app connecting to a separate dev database
after creating an empty test database and telling me a user existed where I
knew it didn't.. took me a while to get past that..)

anyhoo.. can someone please explain the oddities I'm seeing in these tests?

My::Builder works as expected until I call make_immutable on it, then it
returns undef.

My::Builder2 is the same as My::Builder except
 - the 'app' attribute is lazy.
 - it's been made immutable
it works as expected.

My:Builder3 is the same as My::Builder except
 - it's been made immutable
 - I renamed the 'app' attribute as 'attr2'..
it works as expected.

My::Builder4 is the same as My::Builder except
 - attr1 uses lazy_build
 - it's been made immutable
it fails, but it returns attr1's default value

please tell me I'm doing something stupid so I can stop trying to work it
all out.. 8)

cheers,

J

use strict;
use warnings;
use Test::More;

{
    package My::Builder;
    use Moose;

    has attr1 => ( is => 'ro', default => 'default value' );

    has app => ( is => 'ro', builder => '_build_app' );

    sub _build_app{ shift->attr1; }

    sub web_app{
        my $self = shift;
        return sub { $self->app };
    }



    package My::Builder2;
    use Moose;

    has attr1 => ( is => 'ro', default => 'default value' );

    has app => ( is => 'ro', builder => '_build_app', lazy => 1 );

    sub _build_app{ shift->attr1; }

    sub web_app{
        my $self = shift;
        return sub { $self->app };
    }

    __PACKAGE__->meta->make_immutable;


    package My::Builder3;
    use Moose;

    has attr1 => ( is => 'ro', default => 'default value' );

    has attr2 => ( is => 'ro', builder => '_build_attr2' );

    sub _build_attr2{ shift->attr1; }

    sub web_app{
        my $self = shift;
        return sub { $self->attr2 };
    }

    __PACKAGE__->meta->make_immutable;


    package My::Builder4;
    use Moose;

    has attr1 => ( is => 'ro', lazy_build => 1 );
    sub _build_attr1{ 'default value' }

    has app => ( is => 'ro', builder => '_build_app' );

    sub _build_app{ shift->attr1; }

    sub web_app{
        my $self = shift;
        return sub { $self->app };
    }

    __PACKAGE__->meta->make_immutable;

}

my $app = My::Builder->new( attr1 => 'my value' )->web_app;
is $app->(), 'my value', 'no make immutable or lazy ok';

$app = My::Builder2->new( attr1 => 'my value' )->web_app;
is $app->(), 'my value', 'make_immutable with lazy ok';

$app = My::Builder3->new( attr1 => 'my value' )->web_app;
is $app->(), 'my value', 'make_immutable without lazy breaks.. not!';

My::Builder->meta->make_immutable;
$app = My::Builder->new( attr1 => 'my value' )->web_app;
is $app->(), 'my value', 'make_immutable without lazy breaks (returns
undef)';

$app = My::Builder4->new( attr1 => 'my value' )->web_app;
is $app->(), 'my value', 'make_immutable without lazy breaks (returns
default value)';

done_testing();


$ prove -lv t/999-make-immutable-breaksit.t
t/999-make-immutable-breaksit.t ..
ok 1 - no make immutable or lazy ok
ok 2 - make_immutable with lazy ok
ok 3 - make_immutable without lazy breaks.. not!
not ok 4 - make_immutable without lazy breaks (returns undef)

#   Failed test 'make_immutable without lazy breaks (returns undef)'
#   at t/999-make-immutable-breaksit.t line 86.
#          got: undef
#     expected: 'my value'
not ok 5 - make_immutable without lazy breaks (returns default value)

#   Failed test 'make_immutable without lazy breaks (returns default value)'
#   at t/999-make-immutable-breaksit.t line 89.
#          got: 'default value'
#     expected: 'my value'
1..5
# Looks like you failed 2 tests of 5.
Dubious, test returned 2 (wstat 512, 0x200)
Failed 2/5 subtests

Test Summary Report
-------------------
t/999-make-immutable-breaksit.t (Wstat: 512 Tests: 5 Failed: 2)
  Failed tests:  4-5
  Non-zero exit status: 2
Files=1, Tests=5,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.18 cusr  0.01
csys =  0.21 CPU)
Result: FAIL


-- 

Jason Galea
Web Developer

Ph 07 40556926
Mob 04 12345 534
www.eightdegrees.com.au