类的定制
1. 定制自己的float类:
class RoundFloatManual(object): def __init__(self, val): assert isinstance(val, float), "Value must be a float!" self.value = round(val, 2) def __str__(self): #return str(self.value) return '%.2f' % self.value __repr__ = __str__ #rmf = RoundFloatManual(42)#print rmfrmf2 = RoundFloatManual(42.2)print rmf2rmf3 = RoundFloatManual(42.22)print rmf3rmf4 = RoundFloatManual(42.222)print rmf4
class Time60(object): 'Time60 - track hours and minutes' def __init__(self, hr, min): 'Time60 constructor -takes hours and minutes' self.hr = hr self.min = min def __add__(self, other): 'Time60 - overloading the addition operator' return self.__class__(self.hr + other.hr, self.min + other.min) def __iadd__(self, other): 'Time60 - overloading in-place addition' self.hr += other.hr self.min = other.min return self def __str__(self): 'Time60 - string representation' return '%d:%d' % (self.hr, self.min) __repr__ = __str__mon = Time60(10, 30)tue = Time60(11, 15)print mon, tueprint (mon + tue)#print (mon-tue)print id(mon)mon += tueprint monprint id(mon)
