nature-python/python类详解.md

## python类详解.md

      
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              python类详解.md
            
          
    #Python类学习
python是面向对象（OOP）的，类是实现面向对象的方式，与其他语言的类略有不同，python的类比较简单。

创建类

class SchoolMember(object):
  def __init__(self,name,age):
    self.name=name
    self.age=age
  def __str__(self):
    return 'name:%s,age:%s'%(self.name,self.age)

继承类

class Teacher(SchoolMember):
  def __init__(self,name,age,salary):
    SchoolMember(self,name,age)
    self.salary=salary
  def __str__(self):
    return SchoolMember.__str__(self)+',salary:%s'%(self.salary)

类变量和实例变量

class Count():
  count=0
  def __init__(self,count):
    self.count=count
    self.__class__.count+=1
>>>ct1=Count(3)
>>>print ct1.count,Count.count
3 1
>>>ct2=Count(-1)
>>>print ct2.count,Count.count
-1 2


装饰符classmethod和staticmethod

class Methods():
  bar=1
  def normal_method(self):
    print 'normal method'
  @classmethod
  def class_method(cls):
    print 'class method,bar is %s'%cls.bar
    cls().normal_method()
  @staticmethod
  def static_method():
    print 'static method,bar is %s'%Methods.bar
>>>Methods.static_method()
static method,bar is 1
>>>Methods.class_method()
class method,bar is 1
normal method


属性@property（getter,setter,deleter）

#方法一
class Pro(object):
  def __init__(self,x):
    self.__x=x
  def getx(self):
    return self.__x
  def setx(self,value):
    self.__x=value
  def delx(self):
    del self.__x
  x=property(getx,setx,delx)
###############################
#方法二
class Pro(object):
  def __init__(self,x):
    self.__x=x
  @property
  def x(self):
    return self.__x
  @x.setter
  def x(self,value):
    self.__x=value
  @x.deleter
  def x(self):
    del self.__x
>>>pro=Pro(3)
>>>print pro.x
3
>>>pro.x=4
>>>print pro.x
4
>>>del pro.x


新式类和经典类


构造方法
#经典类
class A:
  pass
class A():
  pass
#新式类
class A(object):
  pass


属性继承顺序
#经典类：深度优先
class CA():
  x='a'
class CB(CA):
  pass
class CC(CA):
  x='c'
class CD(CB,CC):
  pass
#>>>c=CD()
#>>>print c.x
#>>>a
#新式类：广度优先
class NA():
  x='a'
class NB(NA):
  pass
class NC(NA):
  x='c'
class ND(NB,NC):
  pass
#>>>n=ND()
#>>>print n.x
#>>>c