Good Z wrote:
Hello,
I am having problem in using is. Here is what i am doing.
Short answer: Use == for equality. Don't use "is". Ever!
(Especially if you are a newbie.)
Longer answer: In a dozen years of programming Python, the only time I
use "is" is when testing for something like
if x is None
but, even then
if x == None
works just as well, and in any case, there is usually a better way.
(See below.)
Don't use "is" until you can explain the following
>>> 11 is 10+1
True
>>> 100001 is 100000+1
False
x=''
if x is None or x is '':
return 1
Both None and an empty string (and empty lists, empty dictionaries,
empty sets, and numeric values of 0 and 0.0) all evaluate a False in an
if statement, so the above if statement can be written as
if not x:
return 1
If you have to test for None, just do
if not x:
If you have to differentiate between a value of None and something that
evaluates to False (e.g., and empty list) then do
if x is None:
# handle None explicitly
elif not x:
# handle empty list
The above statement does not return value 1.
If i changed the above check to
if x == None or x == '':
return 1
Now it works fine.
Any idea. What is happening here. I am using python 2.4.4 on ubuntu.
Mike
------------------------------------------------------------------------
Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try
it now.
<http://us.rd.yahoo.com/evt=51733/*http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ%20>
------------------------------------------------------------------------
--
http://mail.python.org/mailman/listinfo/python-list
--
http://mail.python.org/mailman/listinfo/python-list
