Account | Python Fiddle

class Account(object):
    __slots__ = ['name', '_balance', 'trans']
    num_acs = 0

@staticmethod
    def get_num_acs():
        return Account.num_acs

def __init__(self, name):
        self.name = name
        self._balance = 0
        self.trans = []
        Account.num_acs += 1

def get_balance(self):
        return self._balance

def deposit(self, amount):
        self.trans.append(amount)
        self._balance += amount

def withdraw(self, amount):
        self.trans.append(-amount)
        self._balance -= amount
        
    def get_all_trans(self):
    	return tuple(self.trans)
    
    def __getitem__(self, index):
        return self.trans[index]
    
    def __iadd__(self, amount):
        self.deposit(amount)
        return self
    
    @property
    def balance(self):
    	return self._balance
    
    @balance.setter
    def balance(self, amount):
        print 'setter'
        self._balance = amount

def self_test():
    b1 = Account('john')
    assert b1 is not None
    assert b1.get_balance() == 0
    
    b1.deposit(100)
    assert b1.get_balance() == 100
    b1.withdraw(10)
    assert b1.get_balance() == 90
    
    assert Account.get_num_acs() == 1
    
    assert b1.get_all_trans() == (100, -10)
    assert b1.get_all_trans()[0] == 100
    assert b1[0] == 100 # b1.__class__.__getitem__(b1, 0)
    assert b1[0:2] == [100, -10]
    
    for transaction in b1:
        print transaction
    
    b1 += 200
    assert b1.get_balance() == 290
    assert list(b1) == [100, -10, 200]
    
    print 'ALL TESTS PASSED'
    
    
class PAccount(Account):
	def __init__(self, name, amount):
		Account.__init__(self, name)
		self.deposit(amount)

def plat_test():
    b2 = PAccount('dave', 100)
    assert b2.get_balance() == 100
    
    b3 = Account('sue')
    all_acs = [b2, b3]
    position = 0
    for ac in all_acs:
        if isinstance(ac, Account):
    		position += ac.get_balance()
        else:
            raise TypeError('must be Account')
    print position    
    
    print 'ALL PLATINUM TESTS PASSED'
    
    
class MyMeta(type):
	def __new__(cls, name, bases, att):
		print cls
		print name
		print bases
		print att
        if '__init__' not in att:
			raise TypeError('must implement __init__')
		return type.__new__(cls, name, bases, att)
    
    
class C(object):
    __metaclass__ = MyMeta
    def _init_(self):
        self.mol
        
        
def meta_test():
    obj = C()
    print obj
    
    
if __name__ == '__main__':
	#self_test()
	#plat_test()
    meta_test()

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