None is negative? [Python]

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From: Grant Edwards on 3 Aug 2010 16:32

On 2010-08-03, Grant Edwards <invalid(a)invalid.invalid> wrote:
> On 2010-08-03, wheres pythonmonks <wherespythonmonks(a)gmail.com> wrote:
>
>> I did the google search... I must be blind as I don't see any hits...
>>
>> None is negative in Python? (v2.6)
>
> Not really.
>
>> http://www.google.com/search?ie=UTF-8&q=%22none+is+negative%22+python
>>
>>>>> if None < -9999999.99: print "hi"
>>
>> hi
>>>>>
>>
>>>>> if -9999999 > None: print "hi"
>>
>> hi
>>>>>
>>
>> Is there a way to have the comparison raise an exception?
>
> Use Python 3.x. Or perhaps there's a "from future import xxxx" way to
> do that as well... Is there a list of available "from future"
> features somewhere? I can't seem to figure out how to get Python
> itself to give me a list -- my copy of Python 2.6 insists there's not
> module named future.

Doh! It's "__future__" not "future". And it doesn't appear that you
can import the "unorderable types" behavior.

--
Grant Edwards grant.b.edwards Yow! Uh-oh!! I'm having
at TOO MUCH FUN!!
gmail.com

From: Mithrandir on 3 Aug 2010 16:34

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On 08/03/2010 01:28 PM, Mithrandir wrote:
> On 08/03/2010 01:17 PM, wheres pythonmonks wrote:
>> I did the google search... I must be blind as I don't see any hits...
>
>> None is negative in Python? (v2.6)
>
>> http://www.google.com/search?ie=UTF-8&q=%22none+is+negative%22+python
>
>>>>> if None < -9999999.99: print "hi"
>
>> hi
>>>>>
>
>>>>> if -9999999 > None: print "hi"
>
>> hi
>>>>>
>
>> Is there a way to have the comparison raise an exception?
>
>> W
>
> I believe it's also because None lacks any binary value at all, whereas
> -99999999.99 or 0 have a value in binary.
>
> For example:
>
> if None < 0: print "hi"
>
>>>> hi
>
> if None > 0: print "hi"
>
>>>>
>
> But in human terms, None == 0 and None > -9999999.99.
>
That and/or it works out better in Python 3. :)

- --
People should read more.
https://secure.wikimedia.org/wikipedia/en/wiki/User:MithrandirAgain
"All that is gold does not glitter,
not all those who wander are lost;
the old that is strong does not wither,
deep roots are not reached by the frost.
- From the ashes a fire shall be woken,
a light from the shadows shall spring;
renewed shall be blade that was broken,
the crownless again shall be king."
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From: Chris Rebert on 3 Aug 2010 16:42

From: Ethan Furman on 3 Aug 2010 16:43

Grant Edwards wrote:
> On 2010-08-03, wheres pythonmonks <wherespythonmonks(a)gmail.com> wrote:
>
>> I did the google search... I must be blind as I don't see any hits...
>>
>> None is negative in Python? (v2.6)
>
> Not really.
>
>> http://www.google.com/search?ie=UTF-8&q=%22none+is+negative%22+python
>>
>>>>> if None < -9999999.99: print "hi"
>> hi
>>>>> if -9999999 > None: print "hi"
>> hi
>> Is there a way to have the comparison raise an exception?
>
> Use Python 3.x. Or perhaps there's a "from future import xxxx" way to
> do that as well... Is there a list of available "from future"
> features somewhere? I can't seem to figure out how to get Python
> itself to give me a list -- my copy of Python 2.6 insists there's not
> module named future.
>
In 2.5 & 2.6 it's __future__.

~Ethan~

From: Benjamin Kaplan on 3 Aug 2010 16:45

On Tue, Aug 3, 2010 at 1:29 PM, Grant Edwards <invalid(a)invalid.invalid> wrote:
> On 2010-08-03, wheres pythonmonks <wherespythonmonks(a)gmail.com> wrote:
>
>> I did the google search... I must be blind as I don't see any hits...
>>
>> None is negative in Python? (v2.6)
>
> Not really.
>
>> http://www.google.com/search?ie=UTF-8&q=%22none+is+negative%22+python
>>
>>>>> if None < -9999999.99: print "hi"
>>
>> hi
>>>>>
>>
>>>>> if -9999999 > None: print "hi"
>>
>> hi
>>>>>
>>
>> Is there a way to have the comparison raise an exception?
>
> Use Python 3.x. Or perhaps there's a "from future import xxxx" way to
> do that as well... Is there a list of available "from future"
> features somewhere? I can't seem to figure out how to get Python
> itself to give me a list -- my copy of Python 2.6 insists there's not
> module named future.
>
> --

That would be because it's __future__, not future.

>>> import __future___
>>> help(__future__)
Help on module __future__:

NAME
__future__ - Record of phased-in incompatible language changes.

FILE
c:\program files (x86)\ironpython 2.6 for .net 4.0\lib\__future__.py

DESCRIPTION
Each line is of the form:

FeatureName = "_Feature(" OptionalRelease "," MandatoryRelease ","
CompilerFlag ")"

where, normally, OptionalRelease < MandatoryRelease, and both are 5-tuples
of the same form as sys.version_info:

(PY_MAJOR_VERSION, # the 2 in 2.1.0a3; an int
PY_MINOR_VERSION, # the 1; an int
PY_MICRO_VERSION, # the 0; an int
PY_RELEASE_LEVEL, # "alpha", "beta", "candidate" or "final"; string
PY_RELEASE_SERIAL # the 3; an int
)

OptionalRelease records the first release in which

from __future__ import FeatureName

was accepted.

In the case of MandatoryReleases that have not yet occurred,
MandatoryRelease predicts the release in which the feature will become par
of the language.

Else MandatoryRelease records when the feature became part of the language
in releases at or after that, modules no longer need

from __future__ import FeatureName

to use the feature in question, but may continue to use such imports.

MandatoryRelease may also be None, meaning that a planned feature got
dropped.

Instances of class _Feature have two corresponding methods,
.getOptionalRelease() and .getMandatoryRelease().

CompilerFlag is the (bitfield) flag that should be passed in the fourth
argument to the builtin function compile() to enable the feature in
dynamically compiled code. This flag is stored in the .compiler_flag
attribute on _Future instances. These values must match the appropriate
#defines of CO_xxx flags in Include/compile.h.

No feature line is ever to be deleted from this file.

DATA
__all__ = ['all_feature_names', 'nested_scopes', 'generators', 'divisi...
absolute_import = _Feature((2, 5, 0, 'alpha', 1), (2, 7, 0, 'alpha', 0...
all_feature_names = ['nested_scopes', 'generators', 'division', 'absol...
division = _Feature((2, 2, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0), 8192...
generators = _Feature((2, 2, 0, 'alpha', 1), (2, 3, 0, 'final', 0), 0)
nested_scopes = _Feature((2, 1, 0, 'beta', 1), (2, 2, 0, 'alpha', 0), ...
print_function = _Feature((2, 6, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0)...
unicode_literals = _Feature((2, 6, 0, 'alpha', 2), (3, 0, 0, 'alpha', ...
with_statement = _Feature((2, 5, 0, 'alpha', 1), (2, 6, 0, 'alpha', 0)...

Hm, looks like whatever IronPython is using to display the text is
cutting the lines short. That could be a problem. Anyway, you get the
idea.

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