[Python-Dev] Is XML serialization output guaranteed to be bytewise identical forever?

Raymond Hettinger raymond.hettinger at gmail.com
Wed Mar 20 23:07:49 EDT 2019

> On Mar 20, 2019, at 6:07 PM, Victor Stinner <vstinner at redhat.com> wrote:
> what's the rationale of this backward incompatible change?

Please refrain from abusive mischaracterizations.  It is only backwards incompatible if there was a guaranteed behavior.  Whether there was or not is what this thread is about.  

My reading of this thread was that the various experts did not want to lock in the 3.7 behavior nor did they think the purpose of the XML modules is to produce an exact binary output.  The lxml maintainer is dropping sorting (its expensive and it overrides the order specified by the user). Other XML modules don't sort. It only made sense as a way to produce a deterministic output within a feature release back when there was no other way to do it.

For my part, any agreed upon outcome in fine. I'm not willing be debased further, so I am out of this discussion. It's up to you all to do the right thing.


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