Mega Code Archive
Creating a class hierarchy with an abstract base class
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class Employee:
def __init__( self, first, last ):
if self.__class__ == Employee:
raise NotImplementedError, "Cannot create object of class Employee"
self.firstName = first
self.lastName = last
def __str__( self ):
return "%s %s" % ( self.firstName, self.lastName )
def _isValid( self, value ):
if value < 0:
raise ValueError, "Attribute value (%s) must be positive" % value
else:
return value
def earnings( self ):
raise NotImplementedError, "Cannot call abstract method"
class Boss( Employee ):
def __init__( self, first, last, salary ):
Employee.__init__( self, first, last )
self.weeklySalary = self._isValid( float( salary ) )
def earnings( self ):
return self.weeklySalary
def __str__( self ):
return "%20s: %s" % ( "Boss", Employee.__str__( self ) )
class Developer( Employee ):
def __init__( self, first, last, salary, commission, quantity ):
Employee.__init__( self, first, last )
self.salary = self._isValid( float( salary ) )
self.commission = self._isValid( float( commission ) )
self.quantity = self._isValid( quantity )
def earnings( self ):
return self.salary + self.commission * self.quantity
def __str__( self ):
return "%20s: %s" % ( "Commission Worker", Employee.__str__( self ) )
class Tester( Employee ):
def __init__( self, first, last, wage, quantity ):
Employee.__init__( self, first, last )
self.wagePerPiece = self._isValid( float( wage ) )
self.quantity = self._isValid( quantity )
def earnings( self ):
return self.quantity * self.wagePerPiece
def __str__( self ):
return "%20s: %s" % ( "Piece Worker", Employee.__str__( self) )
class Programmer( Employee ):
def __init__( self, first, last, wage, hours ):
Employee.__init__( self, first, last )
self.wage = self._isValid( float( wage ) )
self.hours = self._isValid( float( hours ) )
def earnings( self ):
if self.hours <= 40:
return self.wage * self.hours
else:
return 40 * self.wage + ( self.hours - 40 ) * self.wage * 1.5
def __str__( self ):
return "%20s: %s" % ( "Hourly Worker",Employee.__str__( self ) )
# main program
employees = [ Boss( "A", "B", 8.00 ),
Developer( "C", "D", 2.0, 3.0, 150 ),
Tester( "E", "F", 2.5, 200 ),
Programmer( "G", "H", 13.75, 40 ) ]
for employee in employees:
print "%s earned $%.2f" % ( employee, employee.earnings() )
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