"Ron Adam" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> To avoid that you either need to define the flag string as a global name
> or use it strictly in the local scope it's defined in. Python will also
> sometimes reuse strings as an optimization instead of creating a second
>
Reinhold Birkenfeld wrote:
> Ron Adam wrote:
>
>
>>>>>> 'abc' is 'abcd'[:3]
>>>False
>>
>>Well of course it will be false... your testing two different strings!
>>And the resulting slice creates a third.
>>
>>Try:
>>
>>ABC = 'abc'
>>
>>value = ABC
>>if value is ABC: # Test if it is the
Ron Adam wrote:
>> >>> 'abc' is 'abcd'[:3]
>> False
>
> Well of course it will be false... your testing two different strings!
> And the resulting slice creates a third.
>
> Try:
>
> ABC = 'abc'
>
> value = ABC
> if value is ABC: # Test if it is the same object
> pass
That's not
Scott David Daniels wrote:
> Ron Adam wrote:
>
>> George Sakkis wrote:
>>
>>> I get:
>>>
>>> None: 0.54952316
>>> String: 0.498000144958
>>> is None: 0.45047684
>>
>>
>>
>> What do yo get for "name is 'string'" expressions?
>
>
> >>> 'abc' is 'abcd'[:3]
> False
Well of course it
Ron Adam wrote:
> George Sakkis wrote:
>
>> I get:
>>
>> None: 0.54952316
>> String: 0.498000144958
>> is None: 0.45047684
>
>
> What do yo get for "name is 'string'" expressions?
>>> 'abc' is 'abcd'[:3]
False
You need to test for equality (==), not identity (is) when
equal t
George Sakkis wrote:
> I get:
>
> None: 0.54952316
> String: 0.498000144958
> is None: 0.45047684
What do yo get for "name is 'string'" expressions?
Or is that a wrong way too?
On my system testing "if string is string" is slightly faster than "if
True/ if False" expressions.
But th
George Sakkis wrote:
>
> How about using the right way of comparing with None ?
>
> x = None
> t = time.time()
> for i in range(100):
> if x is None:
> pass
> print 'is None:',time.time()-t
>
> I get:
>
> None: 0.54952316
> String: 0.498000144958
> is None: 0.450476
Daniel Dittmar <[EMAIL PROTECTED]> wrote:
> In a SQL database, NULL = NULL will always return NULL, which is prety
> much the same as FALSE. Except for NOT, AS NOT NULL is NULL.
SQL's NULL is very much akin to the IEEE NaN (not quite, but close).
--
http://mail.python.org/mailman/listinfo/pytho
Scott David Daniels wrote:
> Testing for None should be an is-test (not just for speed). In
> older pythons the == result wasn't necessarily same as is-test.
> This made sense to me after figuring out NULL in database stuff.
NULL in SQL databases has nothing to do with Python None. I'm quite sure
Ron Adam wrote:
> Here's something interesting:
>
> import time
>
> x = None
> t = time.time()
> for i in range(100):
> if x==None:
> pass
> print 'None:',time.time()-t
>
> x = 'to-end'
> t = time.time()
> for i in range(100):
> if x=='to-end':
> pass
> print 'Str
"Ron Adam" <[EMAIL PROTECTED]> wrote:
> Here's something interesting:
>
> import time
>
> x = None
> t = time.time()
> for i in range(100):
> if x==None:
> pass
> print 'None:',time.time()-t
>
> x = 'to-end'
> t = time.time()
> for i in range(100):
> if x=='to-end':
>
Steven D'Aprano wrote:
> Ron Adam wrote:
>> def count_records(record_obj, start=0, end=len(record_obj)):
>
>
> That would work really well, except that it doesn't work at all.
Yep, and I have to stop trying to post on too little sleep.
Ok, how about... ?
def count_records(record_obj, start
Ron Adam wrote:
> Steven D'Aprano wrote:
>> Er, maybe I'm misunderstanding something here, but surely the most
>> obvious case is for default and special function arguments:
>>
>> def count_records(record_obj, start=0, end=None):
>> if end == None:
>> end = len(record_obj)
>> if s
"Grant Edwards" <[EMAIL PROTECTED]> wrote:
> On 2005-07-07, George Sakkis <[EMAIL PROTECTED]> wrote:
>
> > I guess he means why not define foo as property:
> >
> > class demo(object):
> > foo = property(fget = lambda self: self.v,
> >fset = lambda self,v: setattr(self,'v',v
Duncan Booth wrote:
> Peter Hansen wrote:
>>Tom Anderson wrote:
>>>How about just getting rid of del?
>>
>>Arguing the case for del: how would I, in doing automated testing,
>>ensure that I've returned everything to a "clean" starting point in all
>>cases if I can't delete variables? Sometimes
Daniel Dittmar <[EMAIL PROTECTED]> writes on Wed, 06 Jul 2005 16:12:46 +0200:
> Peter Hansen wrote:
> > Arguing the case for del: how would I, in doing automated testing,
> > ensure that I've returned everything to a "clean" starting point in
> > all cases if I can't delete variables? Sometimes a
Steven D'Aprano wrote:
> Ron Adam wrote:
>
>> Why would you want to use None as an integer value?
>>
>> If a value isn't established yet, then do you need the name defined?
>> Wouldn't it be better to wait until you need the name then give it a
>> value?
>
>
> Er, maybe I'm misunderstanding s
Grant Edwards wrote:
> On 2005-07-07, Ron Adam <[EMAIL PROTECTED]> wrote:
>>It would be a way to set an argument as being optional without
>>actually assigning a value to it.
>>
>>So it would still work like you expect even though v is not
>>bound to anything. Like I said the bigger prob
On 2005-07-07, Ron Adam <[EMAIL PROTECTED]> wrote:
>>class demo:
>> def foo(v=None):
>> if v is not None:
>> self.v = v
>> return self.v
>
> You are really checking if v exists, so having it undefined in
> namespace as the default is consistent with w
Ron Adam wrote:
> Why would you want to use None as an integer value?
>
> If a value isn't established yet, then do you need the name defined?
> Wouldn't it be better to wait until you need the name then give it a value?
Er, maybe I'm misunderstanding something here, but
surely the most obviou
Grant Edwards wrote:
> On 2005-07-07, Ron Adam <[EMAIL PROTECTED]> wrote:
>
>>Grant Edwards wrote:
>>
>>
>>>On 2005-07-06, Ron Adam <[EMAIL PROTECTED]> wrote:
>>>
>>>
>>>
It would be a way to set an argument as being optional without
actually assigning a value to it. The conflict would b
On 2005-07-07, Leif K-Brooks <[EMAIL PROTECTED]> wrote:
> Grant Edwards wrote:
>> On 2005-07-07, Leif K-Brooks <[EMAIL PROTECTED]> wrote:
>>>_NOVALUE = object()
>>>class demo:
>>>def foo(v=_NOVALUE):
>>>if v is _NOVALUE:
>>>return self.v
>>>else:
>>>self.
On 2005-07-07, George Sakkis <[EMAIL PROTECTED]> wrote:
> I guess he means why not define foo as property:
>
> class demo(object):
> foo = property(fget = lambda self: self.v,
>fset = lambda self,v: setattr(self,'v',v))
>
> d = demo()
> d.foo = 3
> print d.foo
In some ways
Grant Edwards wrote:
> On 2005-07-07, Leif K-Brooks <[EMAIL PROTECTED]> wrote:
>>_NOVALUE = object()
>>class demo:
>>def foo(v=_NOVALUE):
>>if v is _NOVALUE:
>>return self.v
>>else:
>>self.v = v
>
>
> Apart from the change in the logic such that the set
"Grant Edwards" wrote:
> In 2005-07-07, Leif K-Brooks <[EMAIL PROTECTED]> wrote:
>
> - Hide quoted text -
> - Show quoted text -
> > Grant Edwards wrote:
> >> 1) So I know whether an parameter was passed in or not. Perhaps
> >>it's not considered good Pythonic style, but I like to use a
> >>
On 2005-07-07, Leif K-Brooks <[EMAIL PROTECTED]> wrote:
> Grant Edwards wrote:
>> 1) So I know whether an parameter was passed in or not. Perhaps
>>it's not considered good Pythonic style, but I like to use a
>>single method for both get and set operations. With no
>>parameters, it's
Grant Edwards wrote:
> 1) So I know whether an parameter was passed in or not. Perhaps
>it's not considered good Pythonic style, but I like to use a
>single method for both get and set operations. With no
>parameters, it's a get. With a parameter, it's a set:
>
>class demo:
>
On 2005-07-07, Ron Adam <[EMAIL PROTECTED]> wrote:
> Grant Edwards wrote:
>
>> On 2005-07-06, Ron Adam <[EMAIL PROTECTED]> wrote:
>>
>>
>>>It would be a way to set an argument as being optional without
>>>actually assigning a value to it. The conflict would be if
>>>there where a global with the
Grant Edwards wrote:
> On 2005-07-06, Ron Adam <[EMAIL PROTECTED]> wrote:
>
>
>>It would be a way to set an argument as being optional without actually
>>assigning a value to it. The conflict would be if there where a global
>>with the name baz as well. Probably it would be better to use a v
On 2005-07-06, Ron Adam <[EMAIL PROTECTED]> wrote:
> It would be a way to set an argument as being optional without actually
> assigning a value to it. The conflict would be if there where a global
> with the name baz as well. Probably it would be better to use a valid
> null value for what e
Reinhold Birkenfeld wrote:
> Ron Adam wrote:
>
>>Ron Adam wrote:
>>
>>
>>>And accessing an undefined name returned None instead of a NameError?
>>
>>I retract this. ;-)
>>
>>It's not a good idea. But assigning to None as a way to unbind a name
>>may still be an option.
>
> IMO, it isn't. This
Ron Adam wrote:
> Ron Adam wrote:
>
>> And accessing an undefined name returned None instead of a NameError?
>
> I retract this. ;-)
>
> It's not a good idea. But assigning to None as a way to unbind a name
> may still be an option.
IMO, it isn't. This would completely preclude the usage of
Ron Adam wrote:
> And accessing an undefined name returned None instead of a NameError?
I retract this. ;-)
It's not a good idea. But assigning to None as a way to unbind a name
may still be an option.
--
http://mail.python.org/mailman/listinfo/python-list
Stian Søiland wrote:
> Yes, and we can make
>
> someunknownlist[] = 2
>
> magically do someunknownlist = list() and append 2.
I hope you're being sarcastic. :)
If not, why don't you like:
some_list = [2]
--
Benji York
--
http://mail.python.org/mailman/listinfo/python-list
On 2005-07-06 18:10:16, Ron Adam wrote:
> But what if assigning a name to None actually unbound it's name?
> And accessing an undefined name returned None instead of a NameError?
Yes, and we can make
someunknownlist[] = 2
magically do someunknownlist = list() and append 2.
Please.
--
S
Steven D'Aprano wrote:
> On Wed, 06 Jul 2005 10:00:02 -0400, Jp Calderone wrote:
>
>
>>On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen <[EMAIL PROTECTED]> wrote:
>>
>>>Tom Anderson wrote:
>>>
How about just getting rid of del? Removal from collections could be
done with a method call, an
On Wed, 06 Jul 2005 10:00:02 -0400, Jp Calderone wrote:
> On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen <[EMAIL PROTECTED]> wrote:
>>Tom Anderson wrote:
>>> How about just getting rid of del? Removal from collections could be
>>> done with a method call, and i'm not convinced that deleting vari
Peter Hansen wrote:
> Tom Anderson wrote:
>> How about just getting rid of del? Removal from collections could be
>> done with a method call, and i'm not convinced that deleting variables
>> is something we really need to be able to do (most other languages
>> manage without it).
>
> Arguing t
Peter Hansen wrote:
> Arguing the case for del: how would I, in doing automated testing,
> ensure that I've returned everything to a "clean" starting point in all
> cases if I can't delete variables? Sometimes a global is the simplest
> way to do something... how do I delete a global if not wit
On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen <[EMAIL PROTECTED]> wrote:
>Tom Anderson wrote:
>> How about just getting rid of del? Removal from collections could be
>> done with a method call, and i'm not convinced that deleting variables
>> is something we really need to be able to do (most ot
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