readonly.pl

use v5.20;

use Class::Anonymous;

my %hash = (
    foo => 'bar',
    baz => 'fuzz',
);

my $obj = make_readonly_obj( %hash );

say $obj->foo;
say $obj->baz;

sub make_readonly_obj {
    my ( %hash ) = @_;
    my $class = class {
        my ( $self ) = @_;
        for my $key ( keys %hash ) {
            $self->( $key, sub { $hash{$key} } );
        }
    };
    return $class->new;
}