List concatenation in python

Question

I know that list is a mutable object in python. Then why does it assign a new location for a list variable when I concatenate list elements.Why doesn't myList add the contents on the original object instead of creating a new object?

list1=[1,2,3,4,5]
def proc(myList):
     myList = myList + [6, 7]
     print(myList)


 print (list1)
 proc(list1)
 print (list1)

score 3 · Accepted Answer · answered Jun 26 '17 at 16:07

3

Because assignment doesn't mutate, it rebinds.

myList.extend([6, 7])

answered Jun 26 '17 at 16:07

Ignacio Vazquez-Abrams

776,304
153
1,341
1,358

or `myList += [6, 7]` - whatever floats his boat – Wondercricket Jun 26 '17 at 16:09
Can you explain rebind? also what's the difference between append and extend? – metasj Jun 26 '17 at 16:09
https://stackoverflow.com/questions/9073995/difference-between-mutation-rebinding-copying-value-and-assignment-operator – Ignacio Vazquez-Abrams Jun 26 '17 at 16:10
http://www-inst.eecs.berkeley.edu/~selfpace/cs9honline/Q2/mutation.html. – metasj Jun 26 '17 at 16:21

List concatenation in python

1 Answers1