Thanks! And what about wrap_cdata, to wrap the content with [I assume] <![CDATA[ ]]> in the approach of your trick ?

Same thing, as long as you know how to do it with a single string. Perhaps something like this:

sub wrap_cdata {
  for (@_) {
    eval { wrap_cdata(@$_); 1 } and next;
    eval { wrap_cdata(values %$_); 1 } and next;
    s/(?<![^>])([^<]+)/<![CDATA[$1]]>/g;
  }
}
[download]

Or not. I don't know why your original unwrap did not use the /g modifier. So please, season to taste.