Hello fellow Monks,

recently I needed to keep some internal state between two method calls to a Moose object. I know now that the way to do that is to create an attribute with a name with a leading underscore. However I tried it like so:

has priv_attr => (
    is        => 'rw',
    isa        => 'Str',
    reader    => '_priv_attr',
    writer    => '_priv_attr'
);
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I used this attribute in a method:

sub do_stuff {
    my $self = shift;
    $self->_priv_attr( 1 );
    $self->_priv_attr;
}
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However, upon calling the method do_stuff the following error occurs:

Attribute (priv_attr) does not pass the type constraint because: Valid
+ation failed for 'Str' with value undef at ./test.pl line 22
        Foo::do_stuff('Foo=HASH(0x8d02c18)') called at ./test.pl line 
+28
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So setting kinda works (in the sense that it doesn't fail) but the value is undefined afterwards. Is there some logic in that? To me it feels like a bug but I'm not very experienced in Moose.

Copy and paste ready code is here:

#!/usr/bin/env perl

use warnings;
use strict;

{
    package Foo;
    use Moose;
    
    has priv_attr => (
        is        => 'rw',
        isa        => 'Str',
        reader    => '_priv_attr',
        writer    => '_priv_attr'
    );
    
    sub do_stuff {
        my $self = shift;
        $self->_priv_attr( 1 );
        $self->_priv_attr;
    }
    
    1;
}

Foo->new->do_stuff;
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