Steve Holden wrote:
.........intain).
Of course, using SQL against a traditional RDBMS will not return rows
with NULL values for salary in a query such as
SELECT name, address WHERE salary < 10000
precisely *because* NULL (absence of value) does not compare with any
value. So you could say that 3.0 is forcing us to acknowledge database
reality ;-)
regards
Steve
on the other hand I find it odd that
cmp(None,None) fails in Python 3 when None==None returns True.
In fact it seems that because None is non-comparable I need to write at least
three of the comparisons at least as two only leads to errors. So now even
though I can sort my objects with None I still cannot sort [None,None]
class A:
def __init__(self,val):
self.val=val
def __lt__(self,other):
if other is None: return False
return self.val<other.val
def __eq__(self,other):
if other is None:
return False
return self.val==other.val
def __gt__(self,other):
if other is None: return True
return self.val>other.val
def __repr__(self):
return 'A(%s)' % self.val
a=A(1)
b=A(2)
print('cmp(a,b) --> %s'%(cmp(a,b)))
print('a<b --> %s'%(a<b))
print('a>b --> %s'%(a>b))
print('a==b --> %s'%(a==b))
print('a<None --> %s'%(a<None))
print('a>None --> %s'%(a>None))
print('a==None --> %s'%(a==None))
print('None<a --> %s'%(None<a))
print('None>a --> %s'%(None>a))
print('cmp(a,None) --> %s'%(cmp(a,None)))
L=[b,a]
L.sort()
print('L --> %s'%(L))
L=[b,a,None]
L.sort()
print('L --> %s'%(L))
--
Robin Becker
--
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