Hi,
I'm following a tutorial about classes, and have created the following
(well, copied it from the manual buy added my own and wifes names)...
class Person:
population=0
def __init__(self,name):
self.name=name
print '(Initialising %s)' % self.name
Person.population += 1
def __del__(self):
print "%s says bye." % self.name
Person.population -= 1
if Person.population == 0:
print "I am the last one"
else:
print "There are still %d people left." % Person.population
def sayHi(self):
'''Greeting by the person.
That's all it does.'''
print "Hi, my name is %s" % self.name
def howMany(self):
if Person.population==1:
print "I am on the only person here."
else:
print "We have %d persons here." % Person.population
Jason=Person("Jason")
Jason.sayHi()
Jason.howMany()
Sophie=Person("Sophie")
Sophie.sayHi()
Sophie.howMany()
Jason.sayHi()
The code, when run, should produce the following...
Hi, my name is Jason.
I am the only person here.
(Initializing Sophie)
Hi, my name is Sophie.
We have 2 persons here.
Hi, my name is Jason.
We have 2 persons here.
Jason says bye.
There are still 1 people left.
Sophie says bye.
I am the last one.
But what I actually get is...
(Initialising Jason)
Hi, my name is Jason
I am on the only person here.
(Initialising Sophie)
Hi, my name is Sophie
We have 2 persons here.
Hi, my name is Jason
We have 2 persons here.
Jason says bye.
There are still 1 people left.
Sophie says bye.
Exception exceptions.AttributeError: "'NoneType' object has no attribute
'popula
tion'" in <bound method Person.__del__ of <__main__.Person instance at
0x0097B53
0>> ignored
I've looked through the code but can't find anything obvious.
I also want to apologise if this isn't the write newsgroup to post on,
but it's the only one I know of. IF anyone knows a good newsgroup, I'd
appreciate it.
TIA
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