#!/usr/bin/perl
use warnings;
use strict;

{   package MyRole;
    use Moo::Role;
    has +x => (is => 'ro');
}

{   package MyObj;
    use Moo;
    has x => (is => 'rw');

    sub finalize {
        'Moo::Role'->apply_roles_to_object($_[0], 'MyRole');
    }
}

my $o = 'MyObj'->new;
$o->x(12);

$o->finalize;
$o->x(13);  # x is a read-only accessor
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Another way is to wrap the accessor:

{   package MyRole;
    use Moo::Role;
    requires 'x';
    before x => sub { die "x is read only" if @_ > 1 };
}
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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