J
Jeff Rollin
Hi there.
I'm working with the Python Tutorial "Byte of Python" at swaroopch.info.
I have created the following file:
------------------------------------------------------------------------
#!/usr/bin/env python
# Filename: objvar.py
class Person:
"""Represents a person."""
population = 0 # class variable
def __init__(self,name):
"""Initializes the person's data."""
self.name = name # object variable
print '(Initializing %s)' % self.name
# When this person is created, he/she adds to the population
Person.population += 1
def __del__(self):
"""I am dying."""
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 say_hi(self):
"""Greeting by the person.
Really, that's all it does."""
print 'Hi, my name is %s.' % self.name
def how_many(cls):
"""Prints the current population."""
if Person.population == 0:
print 'Nobody is alive as of now.'
elif Person.population == 1:
print 'There is just one person here.'
else:
print 'We have %d persons here.' % Person.population
how_many = classmethod(how_many)
#jeff = Person('Jeff')
#jeff.say_hi()
cj = Person('Calamity Jane')
#cj.say_hi()
Person.how_many()
#jeff.say_hi()
Person.how_many()
---------------------------------------------------------------------------------
but when I execute:
% objvar.py
I get the error message:
(Initializing Calamity Jane)
Traceback (most recent call last):
 File "/home/jef/bin/objvar.py", line 49, in <module>
  Person.how_many()
AttributeError: class Person has no attribute 'how_many'
Where am I going wrong?
Many TIA for any help.
I'm working with the Python Tutorial "Byte of Python" at swaroopch.info.
I have created the following file:
------------------------------------------------------------------------
#!/usr/bin/env python
# Filename: objvar.py
class Person:
"""Represents a person."""
population = 0 # class variable
def __init__(self,name):
"""Initializes the person's data."""
self.name = name # object variable
print '(Initializing %s)' % self.name
# When this person is created, he/she adds to the population
Person.population += 1
def __del__(self):
"""I am dying."""
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 say_hi(self):
"""Greeting by the person.
Really, that's all it does."""
print 'Hi, my name is %s.' % self.name
def how_many(cls):
"""Prints the current population."""
if Person.population == 0:
print 'Nobody is alive as of now.'
elif Person.population == 1:
print 'There is just one person here.'
else:
print 'We have %d persons here.' % Person.population
how_many = classmethod(how_many)
#jeff = Person('Jeff')
#jeff.say_hi()
cj = Person('Calamity Jane')
#cj.say_hi()
Person.how_many()
#jeff.say_hi()
Person.how_many()
---------------------------------------------------------------------------------
but when I execute:
% objvar.py
I get the error message:
(Initializing Calamity Jane)
Traceback (most recent call last):
 File "/home/jef/bin/objvar.py", line 49, in <module>
  Person.how_many()
AttributeError: class Person has no attribute 'how_many'
Where am I going wrong?
Many TIA for any help.