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

Antoine Pitrou solipsis at pitrou.net
Tue Mar 19 08:50:56 EDT 2019

Hi Raymond,

As long as the new serialization order is deterministic (i.e. it's the same every run and doesn't depend on e.g. hash randomization), then I think it's fine to change it.

Some more comments / questions:

2). Go into every XML module and add attribute sorting options to each function that generate xml.

What do you mean with "every XML module"? Are there many of them?

Regardless of option chosen, we should make explicit whether on not the Python standard library modules guarantee cross-release bytewise identical output for XML.

IMO we certainly shouldn't. XML is a serialization format used for machine interoperability (even though "human-editable" was one of its selling points at the start, rather misguidingly). However, the output should ideally be stable and deterministic accross all releases of a given bugfix branch.

(i.e., if I run the same code multiple times on all 3.7.x versions, I should get always the same output)

Regards

Antoine.

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