pervasive type constraints

[scpubgit/DX.git] / lib / DX / Role / Value.pm

diff --git a/lib/DX/Role/Value.pm b/lib/DX/Role/Value.pm
index 41ff6dc..ef89517 100644 (file)
--- a/lib/DX/Role/Value.pm
+++ b/lib/DX/Role/Value.pm
@@ -3,9 +3,12 @@ package DX::Role::Value;
 use DX::ActionBuilder::Null;
 use DX::Role;
 
+my $_null = DX::ActionBuilder::Null->new;
+
 has action_builder => (
   is => 'ro',
-  default => 'DX::ActionBuilder::Null',
+  isa => ActionBuilder,
+  default => sub { $_null },
   handles => [ qw(can_set_value aperture_for_set_value action_for_set_value) ],
 );