Python Learning (ix) Magic methods, properties, and iterators

9.1 Preparatory work

All classes of Python 3.0 implicitly become subclasses of object.

9.2 Construction Methods

Create a constructor in Python: Just change the name of the Init method to the Magic version __init__.

class FooBar:     def __init__ (self):         =      >>> f = FooBar ()>>> F.somevar42

　__DEF__: Is a destructor method, but the call time is uncertain, so it is not recommended.

　　9.2.1 overriding general methods and special construction methods

　　A subclass method can override a method of a parent class.

After the constructor is overwritten, if the constructor of the parent class is not called, the properties of some of the parent classes may not be initialized.

The following two summaries are the two solutions that call a superclass construction method.

9.2.2 Call Unbound Superclass construction method

　　

class SongBird (Bird):     def __init__ (self):         //Call the constructor of a super class directly        Bird. __init__ (self)          XXXX

9.2.3 using the Super function

　　

class SongBird (Bird):     def __init__ (self):       Super (Songbrid, self).  __init__  ()        'squawk! '    def Sing (self):        XXX

9.3 Member access

　　9.3.1 Basic sequence and mapping rules

__len__ (self)

__getitem__ (Self.key)

__SETITEM__ (Self.key, value)

__delitem__ (Self.key)

9.3.2 subclass lists, dictionaries, and strings

9.4 More Magic

9.5 Properties

　　9.5.1 Property function

　　Size = Property (GetSize (), SetSize ())

9.5.2 static methods and class member methods

9.5.3 __getattr__, __setattr__ and his friends

　　It is possible to intercept all properties of an object when accessed.

__GETATTRBIUTE__:

__getattr_ (self, name)

__setattr__ (self, name, value)

__delattr__ (self, name)

9.6 iterators

__iter__:

　　9.6.1 iterator Rules

9.6.2 getting sequences from iterators

9.7 Generators

　9.7.1 Creating a generator

9.7.2 Recursive generator

9.7.3 Universal Generator

9.7.4 Generator method

9.7.5 Simulation Generator

9.8 Eight Queen's question

　　9.8.1 Generator and backtracking

9.8.2 problems

9.8.3 Status Indication

9.8.4 Looking for Conflict

9.8.5 Basic situation

9.8.6 need a recursive condition

9.8.7 Packaging

　　

Python Learning (ix) Magic methods, properties, and iterators