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# the bank uses this exception to say there's something wrong:
class BankError(Exception): pass
# Unrestricted account.
class Account(object):
def __init__(s):
s._balance=0.0
def withdraw(s, amount):
s._balance=s._balance-amount
def deposit(s,amount):
s._balance=s._balance+amount
def balance(s):
return s._balance
# Restricted withdrawal account.
class RestrictedAccount(Account):
def withdraw(s, amount):
if amount<=s._balance:
s._balance=s._balance-amount
else:
raise BankError('insufficent balance')
# Abstract bank.
class Bank(object):
def __init__(s):
s.accounts={}
def name(s):
pass # must override this!
def createAccount(s, name):
pass # must override this!
def deleteAccount(s, name):
try:
del s.accounts[name]
except KeyError:
raise BankError('unknown account')
def deposit(s, name, amount):
try:
return s.accounts[name].deposit(amount)
except KeyError:
raise BankError('unknown account')
def withdraw(s, name, amount):
try:
return s.accounts[name].withdraw(amount)
except KeyError:
raise BankError('unknown account')
def balance(s, name):
try:
return s.accounts[name].balance()
except KeyError:
raise BankError('unknown account')
def allAccounts(s):
accs = {}
for name in s.accounts.keys():
accs[name] = s.accounts[name].balance()
return accs
# Special bank: Rabobank. It has unrestricted accounts.
class Rabobank(Bank):
def name(s):
return 'Rabobank'
def createAccount(s,name):
if s.accounts.has_key(name):
raise BankError('Account already exists')
s.accounts[name]=Account()
# Special bank: VSB. It has restricted accounts.
class VSB(Bank):
def name(s):
return 'VSB bank'
def createAccount(s,name):
if s.accounts.has_key(name):
raise BankError('Account already exists')
s.accounts[name]=RestrictedAccount()
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