Question

I thought I could curry a Boolean native type to set to true or false given a function call, but doesn’t seem to work how I expected

updated with traits

    has 'Lock'    => ( 
        is => 'ro', 
        isa => 'Bool', 
        traits => ['Bool'],
        default => 0 ,
        reader  => 'isLocked', 
        handles => {
            lock     => [ set => 1 ],
            unlock => [ set => 0 ],
            flip     => 'toggle',

        }
  ); 

Answer 1

I think you’re looking for Moose::Meta::Attribute::Native::Trait::Bool here, specified by traits => ['Bool'].

When all you have is isa => 'Bool', default => 0, your attribute doesn’t hold an object. You can’t call methods on the number 0, so it can’t handles anything without help from a native trait.

From Moose::Meta::Attribute::Native: “Native delegations allow you to delegate to native Perl data structures as if they were objects.” That means that when you use handles with them, they generate special methods that perform certain operations on the attribute other than calling a method on an object stored within the attribute. The Bool native trait provides set, unset, and toggle methods, which means you can do what you want with:

has 'Lock'    => ( 
    is => 'ro', 
    isa => 'Bool',
    traits => ['Bool'],
    default => 0 ,
    reader  => 'isLocked', 
    handles => {
        lock     => 'set',
        unlock   => 'unset',
        flip     => 'toggle',
    }
 );