PythonでBankAccount

BankAccount

オブジェクト指向向けの「踏み絵」的な課題らしいです。

#encoding:shift-jis
from __future__ import with_statement, division, print_function

class BankAccount(object):
    """
        >>> import bank_account
        >>> a = bank_account.BankAccount(0)
        >>> a.dollars = 200
        >>> a.deposit(50)
        >>> a.dollars
        250
        >>> a.withdraw(100)
        >>> a.dollars
        150
        >>> a.withdraw(200)
        >>> a.dollars
        0
    """
    def __init__(self, dollars):
        self._dollars = dollars
    
    @property
    def dollars(self):
        return self._dollars
    
    @dollars.setter
    def dollars(self, v):
        self._dollars = v if v > 0 else 0
    
    def deposit(self, x):
        self.dollars += x
    
    def withdraw(self, x):
        self.dollars -= x

class StockAccount(BankAccount):
    """
        >>> import bank_account
        >>> stock = bank_account.StockAccount(10, 30)
        >>> stock.numShares
        10
        >>> stock.pricePerShare
        30
        >>> stock.dollars
        300
        >>> stock.dollars = 150
        >>> stock.numShares
        5.0
        >>> stock.dollars = 600
        >>> stock.dollars
        600.0
        >>> stock.numShares
        20.0
        >>> stock.deposit(60)
        >>> stock.dollars
        660.0
        >>> stock.numShares
        22.0
    """
    def __init__(self, numShares, pricePerShare):
        self.numShares = numShares
        self.pricePerShare = pricePerShare
    
    @property
    def dollars(self):
        return self.numShares * self.pricePerShare
    
    @dollars.setter
    def dollars(self, x):
        self.numShares = x / self.pricePerShare

if __name__ == "__main__":
    import doctest
    doctest.testmod()

なんか、普通に書いたら普通に出来ました。
Selfほど短くはなりませんでしたが・・・。

いまいち、このテストの価値がわかりません。