[Python-Dev] Deprecation warning on integer shifts and such

Paul Svensson paul-python@svensson.org
Wed, 14 Aug 2002 15:21:57 -0400 (EDT)

On 14 Aug 2002, Martin v. Loewis wrote:

>Oren Tirosh <oren-py-d@hishome.net> writes:
>> >>> hex(-16711681)
>> '0xff00ffff'
>> >>> hex(-16711681L)
>> '-0xff0001L'		# ??!?!?
>> The hex representation of longs is something I find quite misleading and
>> I think it's also unprecedented.  This wart has bothered me for a long
>> time now but I didn't have any use for it so I didn't mind too much. Now
>> it is proposed to extend this useless representation to ints so I do.
>I don't find it misleading - in fact, the C representation is
>misleading: 0xff00ffff looks like a positive number (it does not have
>a sign) - this is misleading, as the number is, in fact, negative.
>The representation is not misleading: it does not make you believe it
>is something that it actually isn't. It might be surprising, but after
>thinking about it, it should be clear that it is correct: -N is the
>number that, when added to N, gives zero. Indeed:
>>>> -16711681L+0xff0001L
>If you want the bitmask for the lowest 32 bits, you can write
>>>> hex(-16711681L & (2**32-1))
>Notice that -16711681 is a number with an infinite amont of leading
>ones - just as 16711681 is a number with an infinite amount of leading

Just a thougth: if it's true that those using hex() and %x are more
interested in the bit values than the numerical value of the whole number,
would a format like ~0xff000 be easier to interpret (and stop this debate) ?