use constant D50 => [96.42, 100, 82.49];

##</code><code>##

sub D50 () { [96.42, 100, 82.49] }

##</code><code>##

use Readonly;
Readonly::Array my @D50 => (96.42, 100, 82.49);
print $D50[0], "\n";
$D50[0]++;
__END__
96.42
Modification of a read-only value attempted at ...

##</code><code>##

BEGIN {
	my $x = [96.42, 100, 82.49];
	*D50 = sub () { $x };
}

##</code><code>##

use constant D50 => (96.42, 100, 82.49);

##</code><code>##

$ perl -MO=Deparse -e 'use constant X=>[1]; print X->[0]++; print X->[0]++'
use constant ('X', [1]);
print [1]->[0]++;
print [1]->[0]++;
$ perl -le 'use constant X=>[1]; print X->[0]++; print X->[0]++'
1
2