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Re: Inconsistent viewkeys behaviour

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  Re: Inconsistent viewkeys behaviour Terry Reedy <tjreedy@udel.edu> - 2014-04-28 06:28 -0400
    Re: Inconsistent viewkeys behaviour Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-04-29 12:08 +1200

#70673 — Re: Inconsistent viewkeys behaviour

On 4/28/2014 2:22 AM, Joshua Landau wrote:
> Is there any reference for this strange behaviour on Python 2:
>
>      >>> set() < dict().viewkeys()
>      Traceback (most recent call last):
>        File "<stdin>", line 1, in <module>
>      TypeError: can only compare to a set
>      >>> dict().viewkeys() > set()
>      False

The left operand determines the result. The manual specifies that < and 
 > do not have to be consistent. But I suspect that when 3.x dict.keys() 
was backported to 2.7.0, no one thought to update set, whereas the 
backported key view code already had the comparison.

-- 
Terry Jan Reedy

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#70701

Terry Reedy wrote:
> The left operand determines the result. The manual specifies that < and 
>  > do not have to be consistent. But I suspect that when 3.x dict.keys() 
> was backported to 2.7.0, no one thought to update set, whereas the 
> backported key view code already had the comparison.

The question is why set() is raising an exception
instead of returning NotImplemented to give the
other operand a chance.

-- 
Greg

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