[Python-Dev] Multilingual programming article on the Red Hat Developer blog (original) (raw)

R. David Murray rdmurray at bitdance.com
Tue Sep 16 19:46:50 CEST 2014

On Wed, 17 Sep 2014 01:27:44 +1000, Chris Angelico <rosuav at gmail.com> wrote:

On Wed, Sep 17, 2014 at 1:00 AM, R. David Murray <rdmurray at bitdance.com> wrote: > That isn't the case in the email package. The smuggled bytes are not > errors[*], they are literally smuggled bytes.

But they're not characters, which is what Stephen and I were saying - and contrary to what Jim said about treating them as characters. At best, they represent characters but in some encoding other than the one you're using, and you have no idea how many bytes form a character or anything. So you can't, for instance, word-wrap the text, because you can't know how wide these unknown bytes are, whether they represent spaces (wrap points), or newlines, or anything like that. You can't treat them as characters, so while you have them in your string, you can't treat it as a pure Unicode string - it''s a Unicode string with smuggled bytes.

Well, except that I do. The email header parsing algorithms all work fine if I treat the surrogate escaped bytes as 'unknown junk' and just parse based on the valid unicode. (Unless the header is so garbled that it can't be parsed, of course, at which point it becomes an invalid header).

You are right about the wrapping, though. If a header with invalid bytes (and in this scenario we are talking about errors) needs to be wrapped, we have to first decode the smuggled bytes and turn it into an 'unknown-8bit' encoded word before we can wrap the header.

--David

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