Why not just create the subroutine reference like this:

my $code = sub {
    my $dfv = shift;
    my $var = shift;

    return $var !~ /\d+/ ? 1 : 0;
};

my $profile = {
    required => [qw/my_name/],
    constraint_methods => {
        my_name => $code,
    },
};
[download]

No need to create a string first.