[Python-Dev] PEP 557: Data Classes

tds333 at mailbox.org tds333 at mailbox.org
Mon Sep 11 09:43:45 EDT 2017

Hi Eric,

I have on question not addressed yet.
The implementation is based on "__annotations__" where the type is specified.
But "__annotations__" is not always filled. An interpreter version with special optimization
could remove all __annotations__ for performance reasons. (Discussed in other threads)

In this case the dataclass does not work or will there be a fallback?

I know it is a little bit hypothetical because an interpreter with this optimization is
not there yet. I am looking only in the future a bit.
Asking this because type annotations are stated as completely optional for Python.
And this use case will break this assumption.

Personally I am a heavy user of attrs and happy to have a dataclass in the std lib.



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