Python 2.4 removes None data type?

[gaudetteje]

I just read in the 'What's New in Python 2.4' document that the None
data type was converted to a constant:
http://python.org/doc/2.4/whatsnew/node15.html

"""
# None is now a constant; code that binds a new value to the name
"None" is now a syntax error.
"""

So, what's the implications of this? I find the lack of explanation a
little puzzling, since I've written code that compares a variable's
type with the 'None' type. For example, a variable would be
initialized to 'None' and if it went through a loop unchanged, I could
determine this at the end by using a conditional type(var) ==
type(None). What will type(None) return now?

[Warren Postma]

Michael Hoffman wrote:

The fact that True and False are not constants?

Yowza.

a = True
b = False
False = a
True = b
if (1==2)==True:
print "Doom"

[Warren Postma]

Michael Hoffman wrote:

The fact that True and False are not constants?

Yowza.

a = True
b = False
False = a
True = b
if (1==2)==True:
print "Doom"

[Steven Bethard]

Warren Postma wrote:

Michael Hoffman wrote:

The fact that True and False are not constants?

Yowza.

a = True
b = False
False = a
True = b
if (1==2)==True:
print "Doom"

Why stop there when you can really cause some doom:

py> import __builtin__ as bltin
py> bltin.True, bltin.False = bltin.False, bltin.True

As an example of what doom this causes, try typing it at the interactive
prompt, and then see if you can enter anything else. I can't -- the
prompt just locks up. Woo-hoo! Another way to shoot myself (and my
users) in the foot! =)

STeVe

[Brian van den Broek]

Steven Bethard said unto the world upon 2005-03-07 11:55:

Warren Postma wrote:

Michael Hoffman wrote:

The fact that True and False are not constants?

Yowza.

a = True
b = False
False = a
True = b
if (1==2)==True:
print "Doom"

Why stop there when you can really cause some doom:

py> import __builtin__ as bltin
py> bltin.True, bltin.False = bltin.False, bltin.True

As an example of what doom this causes, try typing it at the interactive
prompt, and then see if you can enter anything else. I can't -- the
prompt just locks up. Woo-hoo! Another way to shoot myself (and my
users) in the foot! =)

STeVe

Hi all,

just tried this in IDLE:

IDLE 1.1

import __builtin__ as bltin
bltin.True, bltin.False = bltin.False, bltin.True =============== =============== == RESTART

=============== =============== ==

The restart was done by IDLE itself -- poor thing just gave up. So, it
looks like Steve has found a `commit suicide' command for an IDLE
shell :-)

Best to all,

Brian vdB

[John Machin]

ga********@gmai l.com wrote:

Sheesh... I didn't actually pull the type(None) comparison out of my
code.
Sheesh yourself. Newsgroup readers can't do inspect.hasaclu e('J. Random
Poster'); they rely on duck-typing or goose-typing.
I was simply throwing together a possible situation. Had I
thought about it for more than a second I would have remembered how I
would actually use it.

Indeed.

[Jacek Generowicz]

Warren Postma <wp@tekran__NOS P7M.com> writes:

ga********@gmai l.com wrote:

I just read in the 'What's New in Python 2.4' document that the None
data type was converted to a constant:
http://python.org/doc/2.4/whatsnew/node15.html

Implication: A long standing wart in Python now gone. Its time to
gloat. Are there any really evil glitches LEFT in Python?

Python 2.4 (#1, Dec 1 2004, 14:23:15)
[GCC 3.2.3] on linux2
Type "help", "copyright" , "credits" or "license" for more information.

True, False = False, True
True False

[Jarek Zgoda]

Jacek Generowicz napisa³(a):

Implication : A long standing wart in Python now gone. Its time to
gloat. Are there any really evil glitches LEFT in Python?

Python 2.4 (#1, Dec 1 2004, 14:23:15)
[GCC 3.2.3] on linux2
Type "help", "copyright" , "credits" or "license" for more information.

True, False = False, True
True

False

Ugh, today I've found this in some legacy code (yes, there *is* legacy
code in Python). And I will not touch this module until such syntax
become illegal.

--
Jarek Zgoda
http://jpa.berlios.de/ | http://www.zgodowie.org/