On 24 April 2012 10:18, Robert Kern <robert.k...@gmail.com> wrote: > On 4/24/12 1:03 AM, Tim Delaney wrote: > >> On 24 April 2012 09:08, Devin Jeanpierre <jeanpierr...@gmail.com >> <mailto:jeanpierr...@gmail.com**>> wrote: >> >> On Mon, Apr 23, 2012 at 6:26 PM, Tim Delaney >> <timothy.c.dela...@gmail.com >> <mailto:timothy.c.delaney@**gmail.com<timothy.c.dela...@gmail.com>>> >> wrote: >> > And doing that would make zero sense, because it directly >> contradicts the >> > whole *point* of "is". The point of "is" is to tell you whether or >> not two >> > references are to the same object. This is a *useful* property. >> >> It's useful for mutable objects, yes. How is it useful for immmutable >> things? They behave identically everywhere where you don't directly >> ask the question of "a is b" or "id(a) == id(b)". >> >> >> Not always. NaNs are an exception - they don't even compare equal to >> themselves. >> And hence a very good reason why "is" and == are separate operations. >> > > I think you misread what Devin wrote. "id(a) == id(b)" not "a == b".
No - I was addressing "they behave identically everywhere ..." in the quote. NaNs are a case whre they do not behave identically everywhere. Tim Delaney
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