[Tutor] class question

[Dick Moores]

At 05:35 AM 7/13/2007, Tiger12506 wrote:
> > =======================================
> > class BankAccount(object):
> >    def __init__(self, initial_balance=0):
> >        self.balance = initial_balance
> >    def deposit(self, amount):
> >        self.balance += amount
> >    def withdraw(self, amount):
> >        self.balance -= amount
> >    def overdrawn(self):
> >        return self.balance < 0
> > my_account = BankAccount(15)
> > my_account.withdraw(5)
> > print my_account.balance
> > =========================================
> >
> > This prints the expected "10".
> >
> > My question is, of what use can "overdrawn" be put? If I change the
> > withdrawal amount to 25, it prints the expected "-10", whether the class
> > contains the "overdrawn" function or not.
> >
> > Thanks,
> >
> > Dick Moores
>
>A very good question. Now I have one for you. What does your bank do when
>you try to withdraw money? First, it checks to see if you have the money in
>your account. If you do, it subtracts that out of your balance. Whoever
>wrote that code failed to do the check within the withdraw function.
>
>=======================================
>class BankAccount(object):
>    def __init__(self, initial_balance=0):
>        self.balance = initial_balance
>    def deposit(self, amount):
>        self.balance += amount
>    def withdraw(self, amount):
>        if self.overdrawn():
>           raise "Insufficient Funds Error"
>        self.balance -= amount
>    def overdrawn(self):
>        return self.balance < 0
>my_account = BankAccount(15)
>my_account.withdraw(5)
>print my_account.balance
>=========================================

But when I run that with a withdrawal of 25, it still prints only 
"-10". How have you involved the "overdrawn" function?

Dick