Python Learning 6-objects

Python-an object-oriented language with the largest characteristics of encapsulation, inheritance, and polymorphism.

Encapsulation: Encapsulation can be used directly without caring about how the object is built. Is the principle of hiding excess information from other areas of the global scope

To define a class:

1>>>classPerson ():2     defSetName (self,name):3Self.name =name4     defGetName (self):5         returnSelf.name6     defgreet (self):7         Print 'Hello i am%s'% Self.name

Self: is a reference to the object itself, the difference between a method (a more specialized point, which can be called a binding method), and a function

 1  >>> foo = person ()  2  >>> bar = person ()  3  >>> foo.setname ("   Zhang   " )   4  >>> bar.setname ( " di  Span style= "COLOR: #800000" > " )  5  >>> Foo.greet ()  6  hello I am Zhang  7  >>>  Bar.greet ()  8  hello i am di 

Features can be accessed externally

1 >>> foo.name2'Zhang'3 >>>  Bar.name4'di'5'lu' 6 >>> bar.greet ()7 Hello I am lu

Private methods, outside the class can not be called, internal callable, with "__" start

1 classService:2     def __a(self):3         Print "You can ' t see me"4 5     defB (self):6         Print "You can see me"7Self.__a()8         9>>> s =Service ()Ten>>> S.__a() One  A Traceback (most recent): -File"<pyshell#29>", Line 1,inch<module> -S.__a() theAttributeerror:service instance has no attribute'__a' ->>>s.b () - You can see me -You can't See me

The definition of a class is actually a block of code execution

1 class A: 2     Print " A is created " 3 4     5  is created

Note the difference between the following code

1>>>classMemberCount ():2Members =03     definit (self):4Self.members + = 15    7>>> M1 =MemberCount ()8>>>M1.init ()9>>>m1.membersTen1 One>>> m2 =MemberCount () A>>>M2.init () ->>>m2.members -1 the>>>classMemberCount (): -Members =0 -     definit (self): -Membercount.members + = 1 +         +>>> M1 =MemberCount () A>>>M1.init () at>>>m1.members -1 ->>> m2 =MemberCount () ->>>M2.init () ->>>m2.members -2 in>>>m1.members -2

To specify a super class

1>>>classFilter:2     definit (self):3self.blocked = []4     defFilter (self,sequence):5         return[x forXinchSequenceifX not inchself.blocked]6 7     8>>>classSapmfilter (Filter):9     definit (self):Tenself.blocked = ['SPAM'] One  A          ->>> s =Sapmfilter () ->>>S.init () the>>> S.filter (['SPAM','EFF','A','SPAM'])

Investigate inheritance to see if a class is a subclass of another class, you can use the built-in Issubclass function

1>>>Issubclass (sapmfilter,filter)2 True3>>>Issubclass (filter,sapmfilter)4 False5 #to view the parent class of a known class6>>> Sapmfilter.__bases__7(<class __main__. Filter at 0x0299b0d8>,)8>>> s =Sapmfilter ()9 #to see if an object is an instance of a classTen>>>isinstance (s,sapmfilter) One True A>>>isinstance (s,filter) - True ->>>isinstance (S,STR) theFalse

Multiple superclass multiple inheritance is minimized, and if a method inherits from multiple superclass (that is, two superclass have different methods with the same name), the method in the inheriting class will override the method in the inheriting class.

1>>>classA:2     defAA (self):3         Print "This is a"4 5         6>>>classB:7     defBB (self):8         Print "This is b"9 Ten          One>>>classC (A, b): A     Pass -  ->>> cc =C () the  -  ->>>Cc.aa () -This isa +>>>cc.bb () -This isb +  A>>> c.__bases__ at(<class __main__. A at 0x0299b148>, <class __main__. B at 0x0299b1b8>)

Python Learning 6-objects