Dealing with hex

[Matt Gerrans]

Is there an ideal approach to dealing with the FutureWarning about getting
the hex value of a negative int? I'm using zlib.crc32() which can return
a negative 32-bit int value, so for example print '%x' % zlib.crc32(
buffer ) generates the FutureWarning. I know I could jump through hoops
to coerce the int into a long that will have the same CRC, but is there some
particular recomendation for this (I looked at PEP 237, but there wasn't a
suggestion).

[Derrick 'dman' Hudson]

Re: Dealing with hex

On Wed, 10 Dec 2003 03:49:16 GMT, Matt Gerrans wrote:[color=blue]
> Is there an ideal approach to dealing with the FutureWarning about getting
> the hex value of a negative int? I'm using zlib.crc32() which can return
> a negative 32-bit int value, so for example print '%x' % zlib.crc32(
> buffer ) generates the FutureWarning. I know I could jump through hoops
> to coerce the int into a long that will have the same CRC, but is there some
> particular recomendation for this (I looked at PEP 237, but there wasn't a
> suggestion).[/color]

Hoops? For example :
print "%x" % long( zlib.crc32( buffer ) )

That seems simple enough to me.

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[Dan Bishop]

Re: Dealing with hex

Derrick 'dman' Hudson <dman@dman13.dy ndns.org> wrote in message news:<6clka1-ksi.ln1@dman13. dyndns.org>...[color=blue]
> On Wed, 10 Dec 2003 03:49:16 GMT, Matt Gerrans wrote:[color=green]
> > Is there an ideal approach to dealing with the FutureWarning about getting
> > the hex value of a negative int? I'm using zlib.crc32() which can return
> > a negative 32-bit int value, so for example print '%x' % zlib.crc32(
> > buffer ) generates the FutureWarning. I know I could jump through hoops
> > to coerce the int into a long that will have the same CRC, but is there some
> > particular recomendation for this (I looked at PEP 237, but there wasn't a
> > suggestion).[/color]
>
> Hoops? For example :
> print "%x" % long( zlib.crc32( buffer ) )
>
> That seems simple enough to me.[/color]

Or if you wanted the old semantics:

def unsigned(n):
return n & 0xFFFFFFFFL

print "%x" % unsigned(zlib.c rc32(buffer))

[Matt Gerrans]

Re: Dealing with hex

Derrick 'dman' Hudson wrote:[color=blue][color=green]
> > Hoops? For example :
> > print "%x" % long( zlib.crc32( buffer ) )
> >
> > That seems simple enough to me.[/color][/color]

Simple indeed. In fact it's so simple it doesn't work:
[color=blue][color=green][color=darkred]
>>> print "%x" % long( zlib.crc32('tes t') )[/color][/color][/color]
-278081f4

Dan Bishop wrote:[color=blue]
> Or if you wanted the old semantics:
>
> def unsigned(n):
> return n & 0xFFFFFFFFL
>
> print "%x" % unsigned(zlib.c rc32(buffer))[/color]

This avoids the FutureWarning, but the PEP mentions that the L-suffix
notation will also be phased out, so I wanted to avoid that in the solution
and that can be done like this:

def unsigned32(n): return n & 4294967295

since the large decimal of 0xffffffff value will automatically be a long.

It seems kind of clunky to have to throw this extra function call into the
mix whenever dealing with 32-bit values. I don't think 32-bit values will
be made obsolete by 64-bit systems for quite a while to come. This
particular update to Python seems a little pie-in-the-sky and un-pragmatic.