Python中的复制操作及copy模块中的浅拷贝与深拷贝方法

a = [1, 2, 3]
b = a

# [1, 2, 3]
print b 

b[0] = 5 

# [5, 2, 3]
print b 

# [5, 2, 3]
print a 

a = [1, 2, 3]
b = a[:]
b[0] = 4

# [1, 2, 3]
# [4, 2, 3]
print a
print b

a = [[1,2,3], 4, 5]
b = a[:]
b[1] = 0 

# [[1,2,3], 4, 5]
# [[1,2,3], 0, 5]
print a
print b

a = [[1,2,3], 4, 5]
b = a[:]
b[0][0] = 5

# [[5,2,3], 4, 5]
# [[5,2,3], 4, 5]
print a
print b
b = a[:]

#coding=gbk
import copy
l1 = [1, 2, [3, 4]]
l2 = copy.copy(l1)
print l1
print l2
l2[2][0] = 50
print l1
print l2

[1, 2, [3, 4]]
[1, 2, [3, 4]]
[1, 2, [50, 4]]
[1, 2, [50, 4]]

import copy
l1 = [1, 2, [3, 4]]
l2 = copy.deepcopy(l1)
print l1
print l2
l2[2][0] = 50
print l1
print l2

[1, 2, [3, 4]]
[1, 2, [3, 4]]
[1, 2, [3, 4]]
[1, 2, [50, 4]]

class CopyObj(object):
  def __repr__(self):
    return "CopyObj"
  
  def __copy__(self):
    return "Hello"
obj = CopyObj()
obj1 = copy.copy(obj)
print obj
print obj1

CopyObj
Hello