[Numpy-discussion] in the NA discussion, what can we agree on?
Mon Nov 7 05:37:46 CST 2011
Nathaniel Smith writes:
> So assignment is not destructive -- the old value is retained as the "payload".
I never assumed (and I think it is also the case for others) that the payload
was retaining the old value. In fact, AFAIR, the payloads were introduced as a
way of having more than one special value that (if wanted by the user) can be
handled differently depending on the payload.
Note that while you're assuming "IGNORED(x)" means a value that is ignoring the
"x" original value, you're never writing "MISSING(x)" to retain the original
value that is now missing.
Thus I think that decoupling the payload from the "previous value" concept makes
it all consistent regardless of the destructiveness property.
That's one of the reasons why I used the "special value" concept since the
beginning, so that no assumption can be made about its propagation and
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
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