The Python class's property access control and built-in function overrides enable advanced functionality and @property

I. Access control for class attributes

Python class is really profound, so let's review the property's access control as the open (Fu) field (xi).

First _varname is accessible, __varname is not directly accessible (the principle is __varname becomes _classname__varname)

1>>>classA:2... _aa = 13...__BB= 24 ...5>>>6>>>7>>> C =A ()8>>>C._aa91Ten>>> c.__BB One Traceback (most recent): AFile"<stdin>", Line 1,inch<module> -ATTRIBUTEERROR:A instance has no attribute'__BB' ->>>C._A__BB the2 - >>>                                                                                                                          

Second, the built-in function:

Do not want to verbose directly on the code, comments to explain:

1 classPerson (object):2     def __init__(self,name):3Self.name =name4     def __str__(self):5             return  "<class:person name:%s>"%Self.name6     def __repr__(self):7             return  "<Name:%s>"%Self.name8 9Tom = Person ("Tom")TenPrint repr (Tom) One PrintTom

1 classPerson (object):2     def __init__(self,name,age):3Self.name =name4Self.age = Age5     def __str__(self):6         return  "<class:person name:%s>"%Self.name7     def __repr__(self):8         return "<Name:%s>"%Self.name9     def __len__(self):Ten         returnSelf.age OneTom = Person ("Tom", 20) A Printrepr (Tom) - PrintTom - PrintLen (Tom)

And of course there are many:

1 def __iter__(self):#overriding built-in iteration capabilities2RET =do_something ()3     returnret4 5 def __getitem__(self):#Add the following table to object function6     Pass7 8 def __getattr__(self):#to increase the processing of their own properties9     PassTen  One def __call__(self):#Direct instances as function calls A     Pass - """ - class A: the def __call__ (self): - print "OK" - a = a () - A () + >>> OK - """

Thirdly, @property method is attributed:

1 classStudent:2     def __init__(self,name):3Self.name =name4 @property5     defAge (self):6         returnSelf.age7 @age. Setter8     defAge (self,age):9Self.age = AgeTen  One """ A A = Student ("Stu") - a.age = - A.age the >>> - """

The Python class's property access control and built-in function overrides enable advanced functionality and @property