Question

Please help me understand this. I created a really simple program to try to understand classes.

class One(object):
    def __init__(self, class2):
        self.name = 'Amy'
        self.age = 21
        self.class2 = class2

    def greeting(self):
        self.name = raw_input("What is your name?: ")
        print 'hi %s' % self.name

    def birthday(self):
        self.age = int(raw_input("What is your age?: "))
        print self.age 

    def buy(self):
        print 'You buy ', self.class2.name

class Two(object):
    def __init__(self): 
        self.name = 'Polly'
        self.gender = 'female'

    def name(self):
        self.gender = raw_input("Is she male or female? ")
        if self.gender == 'male'.lower():
            self.gender = 'male'
        else:
            self.gender = 'female'

        self.name = raw_input("What do you want to name her? ")

        print "Her gender is %s and her name is %s" % (self.gender, self.name)

Polly = Two()
Amy = One(Polly) 
# I want it to print 


Amy.greeting()
Amy.buy() 
Amy.birthday()

THE PROBLEM CODE

Polly.name() # TypeError: 'str' object is not callable
Two.name(Polly)# Works. Why?

Why does calling the method on the class instance Polly not work? I’m pretty lost. I’ve looked at http://mail.python.org/pipermail/tutor/2003-May/022128.html and other Stackoverflow questions similiar to this, but I’m not getting it. Thank you so much.

Answer 1

The class Two has an instance method name(). So Two.name refers to this method and the following code works fine:

Polly = Two()
Two.name(Polly)

However in __init__(), you override name by setting it to a string, so any time you create a new instance of Two, the name attribute will refer to the string instead of the function. This is why the following fails:

Polly = Two()      # Polly.name is now the string 'Polly'
Polly.name()       # this is equivalent to 'Polly'()

Just make sure you are using separate variable names for your methods and your instance variables.