Mutable objects, immutable objects

Immutable objects are strings, tuples, and so on

mutable objects are lists, dictionaries, collections, and so on.

A shallow copy simply adds a new object reference to the existing memory. ,

A deep copy is a re-application of a new memory so that this is a reference to the new memory address of the new object.

Frequently occurs for variable object references.

Consider the following two-segment code:

Code 1

L = [] forIinchRangeTen): L.append ({'Num': i}) Print (L) Result: [{'Num':0}, {'Num':1}, {'Num':2}, {'Num':3}, {'Num':4}, {'Num':5}, {'Num':6}, {'Num':7}, {'Num':8}, {'Num':9}]

Code 2

L =[]a= {'Num':0} forIinchRangeTen): a['Num'] =i l.append (a) print (l) print ('ID (l[0]):', ID (l[0]),'\nid (l[1]):', ID (l[1]) Result: [{'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}, {'Num':9}]id (l[0]) :4542112ID (l[1]) :4542112

Conclusion:

The newly added object in L.append in code 1 is the newly created object,

The newly added object in L.append in code 2 is dictionary a, l[new] = A, l[new] is a new reference to the memory address of a, and all L[new] point to the same memory address. While dictionary A is a mutable object, the change of the data in the memory address after a changes. ，

Mutable objects, immutable objects