Magic methods for classes in Python

Objective: To learn the magic methods of class in python to improve the efficiency of programming.

Environment: Ubuntu 16.4 python 3.5.2

Learning class is bound to come into contact with its magic methods, such as commonly used __init__, the form is preceded by a double underline. In addition to this necessary, there are other useful methods, the following is about to introduce.

Method of Operation Magic:

__add__ as +

__sub__ AS-

__mul__ as *

__truediv__ AS/

__floordiv__ AS//

__mod__ as%

__pow__ as * *

__and__ as A &

__xor__ as ^

__or__ used as |

To illustrate:

Class Specialstring:def __init__ (Self, cont): Self.cont = Cont def __truediv__ (self, Other): line = ' = ' * Len (Other.cont) return Rn.join ([Self.cont, Line, other.cont]) spam = specialstring (' spam ') Hello = Specialstring (' Helo world! ') Print (Spam/hello) # results >>>spam============hello world!>>>

x + y is equivalent to x.__add__ (y), but if X does not have a __add__ method, and X and Y are different classes, then it checks if Y has __radd__, is represented as y.__radd__ (x), does not appear typeerror, and all Megic Methods all have R methods.

Compare Magic methods:

__lt__ as a <

__le__ as <=

__eq__ as = =

__ne__ as! =

__gt__ as a >

__ge__ as >=

If the __ne__ does not exist, the direction of the __eq__ is returned.

To illustrate:

class specialstring:    def __init__ (Self, cont):         self.cont = cont             def __gt__ (self, other):         for index  in range (Len (other.cont)  + 1):             result = other.cont[:index] +  ' > '  + self.cont             result +=  ' > '  + other.cont[ Index:]            print (Result)          spam = specialstring (' spam ') eggs = specialstring (' eggs ') spam  > eggs# result>>>>spam>eggse>spam>ggseg>spam>gsegg>spam> Seggs>spam>>&gT; a magic method similar to a container: __len__ used as  len () __getitem__  as an index __setitem__  as an allocation index __delitem__  as a drop index __iter__   used as an iterative object __contains__ as an in illustration: class vaguelist:    def __init__ (self,  Cont):        self.cont = cont             def __getitem__ (Self, index):         return self.cont[index + random.randint ( -1, 1)]         def __len__ (self):         return  random.randint (0, len (Self.cont)  * 2)          Vague_list = vaguelist ([' A ',  ' B ',  ' C ',  ' D ',  ' E ']) print (len (vague_list)) print (len (vague_list)) Print (vague_list[2]) print (vague_list[2]) #result >>>22CD>>>

Reference Document Source: Sololearn

This article is from the "Rickyhul" blog, make sure to keep this source http://rickyh.blog.51cto.com/10934856/1952167

Magic methods for classes in Python