class TenLop:
   'Phan documentation string cho lop la tuy y'
   class_suite

class Sinhvien:
   'Class co so chung cho tat ca sinh vien'
   svCount = 0

   def __init__(self, ten, hocphi):
      self.ten = ten
      self.hocphi = hocphi
      Sinhvien.svCount += 1
   
   def displayCount(self):
     print "Tong so Sinh vien %d" % Sinhvien.svCount

   def displaySinhvien(self):
      print "Ten : ", self.ten,  ", Hoc phi: ", self.hocphi

"Lenh nay tao doi tuong dau tien cua lop Sinhvien"
sv1 = Sinhvien("Hoang", 4000000)
"Lenh nay tao doi tuong thu hai cua lop Sinhvien"
sv2 = Sinhvien("Huong", 4500000)

sv1.displaySinhvien()
sv2.displaySinhvien()
print "Tong so Sinh vien %d" % Sinhvien.svCount

class Sinhvien:
   'Class co so chung cho tat ca sinh vien'
   svCount = 0

   def __init__(self, ten, hocphi):
      self.ten = ten
      self.hocphi = hocphi
      Sinhvien.svCount += 1
   
   def displayCount(self):
     print "Tong so Sinh vien %d" % Sinhvien.svCount

   def displaySinhvien(self):
      print "Ten : ", self.ten,  ", Hoc phi: ", self.hocphi

"Lenh nay tao doi tuong dau tien cua lop Sinhvien"
sv1 = Sinhvien("Hoang", 4000000)
"Lenh nay tao doi tuong thu hai cua lop Sinhvien"
sv2 = Sinhvien("Huong", 4500000)
sv1.displaySinhvien()
sv2.displaySinhvien()
print "Tong so Sinh vien %d" % Sinhvien.svCount

Ten :  Hoang ,Hoc phi:  4000000
Ten :  Huong ,Hoc phi:  4500000
Tong so Sinh vien 2

sv1.tuoi = 21  # Them mot thuoc tinh 'tuoi'.
sv1.tuoi = 20  # Sua doi thuoc tinh 'tuoi'.
del sv1.tuoi  # Xoa thuoc tinh 'tuoi'.

hasattr(sv1, 'tuoi')    # Tra ve true neu thuoc tinh 'tuoi' ton tai
getattr(sv1, 'tuoi')    # Tra ve gia tri cua thuoc tinh 'tuoi'
setattr(sv1, 'tuoi', 20) # Thiet lap thuoc tinh 'tuoi' la 20
delattr(sv1, 'tuoi')    # Xoa thuoc tinh 'tuoi'

class Sinhvien:
   'Class co so chung cho tat ca sinh vien'
   svCount = 0

   def __init__(self, ten, hocphi):
      self.ten = ten
      self.hocphi = hocphi
      Sinhvien.svCount += 1
   
   def displayCount(self):
     print "Tong so Sinh vien %d" % Sinhvien.svCount

   def displaySinhvien(self):
      print "Ten : ", self.ten,  ", Hoc phi: ", self.hocphi

print "Sinhvien.__doc__:", Sinhvien.__doc__
print "Sinhvien.__name__:", Sinhvien.__name__
print "Sinhvien.__module__:", Sinhvien.__module__
print "Sinhvien.__bases__:", Sinhvien.__bases__
print "Sinhvien.__dict__:", Sinhvien.__dict__

Sinhvien.__doc__: Class co so chung cho tat ca sinh vien
Sinhvien.__name__: Sinhvien
Sinhvien.__module__: __main__
Sinhvien.__bases__: ()
Sinhvien.__dict__: {'__module__': '__main__', 'displayCount':
, 'svCount': 2, 
'displaySinhvien': , 
'__doc__': 'Class co so chung cho tat ca sinh vien', 
'__init__': }

a = 40      # Tao doi tuong <40>
b = a       # Tang so tham chieu cua <40> 
c = [b]     # Tang so tham chieu cua <40> 

del a       # Giam so tham chieu cua <40>
b = 100     # Giam so tham chieu cua <40> 
c[0] = -1   # Giam so tham chieu cua <40>

class Point:
   def __init( self, x=0, y=0):
      self.x = x
      self.y = y
   def __del__(self):
      class_name = self.__class__.__name__
      print class_name, "destroyed"

pt1 = Point()
pt2 = pt1
pt3 = pt1
print id(pt1), id(pt2), id(pt3) # in id cua doi tuong
del pt1
del pt2
del pt3

3083401324 3083401324 3083401324
Point destroyed

class Tenlopcon (LopCha1[, LopCha2, ...]):
   'Phan documentation string cua Class la tuy y'
   class_suite

class Parent:        # dinh nghia lop cha
   parentAttr = 100
   def __init__(self):
      print "Goi constructor cua lop cha"

   def parentMethod(self):
      print 'Goi phuong thuc cua lop cha'

   def setAttr(self, attr):
      Parent.parentAttr = attr

   def getAttr(self):
      print "Thuoc tinh cua lop cha :", Parent.parentAttr

class Child(Parent): # dinh nghia lop con
   def __init__(self):
      print "Goi constructor cua lop con"

   def childMethod(self):
      print 'Goi phuong thuc cua lop con'

c = Child()          # instance cua lop con
c.childMethod()      # lop con goi phuong thuc cua no
c.parentMethod()     # goi phuong thuc cua lop cha
c.setAttr(200)       # tiep tuc goi phuong thuc cua lop cha
c.getAttr()          # tiep tuc goi phuong thuc cua lop cha

Goi constructor cua lop con
Goi phuong thuc cua lop con
Goi phuong thuc cua lop cha
Thuoc tinh cua lop cha : 200

class A:        # dinh nghia lop A
.....

class B:         # dinh nghia lop B
.....

class C(A, B):   # lop con cua A va B
.....

class Parent:        # dinh nghia lop cha
   def myMethod(self):
      print 'Goi phuong thuc cua lop cha'

class Child(Parent): # dinh nghia lop con
   def myMethod(self):
      print 'Goi phuong thuc cua lop con'

c = Child()          # instance cua lop con
c.myMethod()         # lop con goi phuong thuc duoc ghi de

Goi phuong thuc cua lop con

class Vector:
   def __init__(self, a, b):
      self.a = a
      self.b = b

   def __str__(self):
      return 'Vector (%d, %d)' % (self.a, self.b)
   
   def __add__(self,other):
      return Vector(self.a + other.a, self.b + other.b)

v1 = Vector(2,10)
v2 = Vector(5,-2)
print v1 + v2

Vector(7,8)

class JustCounter:
   __secretCount = 0
  
   def count(self):
      self.__secretCount += 1
      print self.__secretCount

counter = JustCounter()
counter.count()
counter.count()
print counter.__secretCount

1
2
Traceback (most recent call last):
  File "test.py", line 12, in 
    print counter.__secretCount
AttributeError: JustCounter instance has no attribute '__secretCount'

.........................
print counter._JustCounter__secretCount

1
2
2