python继承和抽象类的实现方法
本文实例讲述了python继承和抽象类的实现方法。分享给大家供大家参考。
具体实现方法如下：
#!/usr/local/bin/python
#Fig9.9:fig09_09.py
#Creatingaclasshierarchywithanabstractbaseclass.
classEmployee:
"""AbstractbaseclassEmployee"""
def__init__(self,first,last):
"""Employeeconstructor,takesfirstnameandlastname.
NOTE:CannotcreateobjectofclassEmployee."""
ifself.__class__==Employee:
raiseNotImplementedError,\
"CannotcreateobjectofclassEmployee"
self.firstName=first
self.lastName=last
def__str__(self):
"""StringrepresentationofEmployee"""
return"%s%s"%(self.firstName,self.lastName)
def_checkPositive(self,value):
"""Utilitymethodtoensureavalueispositive"""
ifvalue<0:
raiseValueError,\
"Attributevalue(%s)mustbepositive"%value
else:
returnvalue
defearnings(self):
"""Abstractmethod;derivedclassesmustoverride"""
raiseNotImplementedError,"Cannotcallabstractmethod"
classBoss(Employee):
"""Bossclass,inheritsfromEmployee"""
def__init__(self,first,last,salary):
"""Bossconstructor,takesfirstandlastnamesandsalary"""
Employee.__init__(self,first,last)
self.weeklySalary=self._checkPositive(float(salary))
defearnings(self):
"""ComputetheBoss'spay"""
returnself.weeklySalary
def__str__(self):
"""StringrepresentationofBoss"""
return"%17s:%s"%("Boss",Employee.__str__(self))
classCommissionWorker(Employee):
"""CommissionWorkerclass,inheritsfromEmployee"""
def__init__(self,first,last,salary,commission,quantity):
"""CommissionWorkerconstructor,takesfirstandlastnames,
salary,commissionandquantity"""
Employee.__init__(self,first,last)
self.salary=self._checkPositive(float(salary))
self.commission=self._checkPositive(float(commission))
self.quantity=self._checkPositive(quantity)
defearnings(self):
"""ComputetheCommissionWorker'spay"""
returnself.salary+self.commission*self.quantity
def__str__(self):
"""StringrepresentationofCommissionWorker"""
return"%17s:%s"%("CommissionWorker",
Employee.__str__(self))
classPieceWorker(Employee):
"""PieceWorkerclass,inheritsfromEmployee"""
def__init__(self,first,last,wage,quantity):
"""PieceWorkerconstructor,takesfirstandlastnames,wage
perpieceandquantity"""
Employee.__init__(self,first,last)
self.wagePerPiece=self._checkPositive(float(wage))
self.quantity=self._checkPositive(quantity)
defearnings(self):
"""ComputePieceWorker'spay"""
returnself.quantity*self.wagePerPiece
def__str__(self):
"""StringrepresentationofPieceWorker"""
return"%17s:%s"%("PieceWorker",
Employee.__str__(self))
classHourlyWorker(Employee):
"""HourlyWorkerclass,inheritsfromEmployee"""
def__init__(self,first,last,wage,hours):
"""HourlyWorkerconstructor,takesfirstandlastnames,
wageperhourandhoursworked"""
Employee.__init__(self,first,last)
self.wage=self._checkPositive(float(wage))
self.hours=self._checkPositive(float(hours))
defearnings(self):
"""ComputeHourlyWorker'spay"""
ifself.hours<=40:
returnself.wage*self.hours
else:
return40*self.wage+(self.hours-40)*\
self.wage*1.5
def__str__(self):
"""StringrepresentationofHourlyWorker"""
return"%17s:%s"%("HourlyWorker",
Employee.__str__(self))
#mainprogram
#createlistofEmployees
employees=[Boss("John","Smith",800.00),
CommissionWorker("Sue","Jones",200.0,3.0,150),
PieceWorker("Bob","Lewis",2.5,200),
HourlyWorker("Karen","Price",13.75,40)]
#printEmployeeandcomputeearnings
foremployeeinemployees:
print"%searned$%.2f"%(employee,employee.earnings())
输出结果如下：
Boss:JohnSmithearned$800.00
CommissionWorker:SueJonesearned$650.00
PieceWorker:BobLewisearned$500.00
HourlyWorker:KarenPriceearned$550.00
希望本文所述对大家的Python程序设计有所帮助。