Application Example of prototype in design mode in Python Program

This article mainly introduces the application example of the prototype mode in the design mode in the Python program. This article mainly emphasizes the use of the shortest copy and deep copy in object replication. For more information, see Prototype:
The prototype instance specifies the type of the object to be created and creates a new object by copying the prototype.
The prototype mode is essentially a clone object. Therefore, when the initialization operations of objects are complex, it is very practical and can greatly reduce the time consumption and improve the performance, because "you do not need to reinitialize objects, instead, it dynamically obtains the running state of the object ".

Application features:
A large number of modifications are required based on a basic prototype to obtain the new original type.

Structural Features:
Object replication mechanism, that is, shallow replication and deep replication.

Example 1:

#!/usr/bin/env python  #encoding: utf-8  from copy import copy, deepcopy  class test_obj:   def __init__(self, id):     self.id = id    class proto_type:   def __init__(self, name, id):     self.name = name     self.obj = test_obj(id)      def display(self):     print self.name     print self.obj.id    def clone(self):     return copy(self)      def deep_clone(self):     return deepcopy(self)        if '__main__' == __name__:    obj1 = proto_type('name1', 1)   obj2 = obj1.clone()   obj3 = obj1.deep_clone()   obj2.name = 'name2'   obj2.obj.id = 2   obj3.name = 'name3'   obj3.obj.id = 3    obj1.display()   obj2.display()   obj3.display()   print obj1.__class__   print obj2.__class__   print obj3.__class__  

Result:

Name1 2 # Because obj2 is a light copy, the object is not copied. As a result, the modification of the new object affects the original object Value name2 2 name3 3 # because it is a deep copy, so it will not affect the old object _ main __. proto_type _ main __. proto_type _ main __. proto_type

Here we will review the knowledge points of the basic Python programming on the shortest copy and deep copy:
Shallow Copy ):
The field of the object is copied, but the object referenced by the field is not copied. The Copied object and the source object only share the same name, but they share the same entity.
Deep copy ):
The object referenced by fields in the object instance is also copied.

Well, based on the above, let's look at an example:

Example 2:

# Encoding = UTF-8 ## by panda # prototype mode import copy def printInfo (info): print unicode (info, 'utf-8 '). encode ('gbk') # copy Interface class ICloneable: def shallowClone (self): return copy. copy (self) def deepClone (self): return copy. deepcopy (self) # Work Experience class WorkExperience (ICloneable): workData = "" company = "" pass # Resume class Resume (ICloneable ): name = "" sex = 'unknown 'age = 0 work = None def _ init _ (self, name, work = WorkExperience (): self. name = name self. work = work; def setPersonInfo (self, sex, age): self. sex = sex self. age = age def setWorkExperience (self, workData, company): self. work. workData = workData self. work. company = company def display (self): printInfo ('% s, % s, % d' % (self. name, self. sex, self. age) printInfo ('% s, % s' % (self. work. workData, self. work. company) def clientUI (): a = Resume ('daybird '). setPersonInfo ('male', 29). setWorkExperience ("1998-2000", "XX Company") # copy B =. shallowClone () B. setWorkExperience ("2000-2006", "YY Company") # Deep copy c =. deepClone () c. setWorkExperience ("2006-2009", "ZZ company") B. display (). display () c. display () return if _ name _ = '_ main _': clientUI ();