Why can't I reassign a list (passed as a paramater) in a function?

Question

According to my understanding, both functions should have changed list since lists are mutable but only foo() did so.

def foo(myList):
  myList[0] = 3
  
def bar(myList):
  myList = [3,2,1]

list = [1,2,3]
print(list)

foo(list)
print(list)

bar(list)
print(list)

`myList` is a name for an object. It only exists in the scope of the function. In `bar` you are changing the name, not the list. — Peter Wood, Jul 15 '22 at 16:04

score 3 · Accepted Answer · answered Jul 15 '22 at 16:06

Print the id may help you to understand it:

def foo(myList):
  myList[0] = 3
  print(id(myList))
  
def bar(myList):
  myList = [3,2,1]
  print(id(myList))

list = [1,2,3]
print(list)
print(id(list))

foo(list)
print(list)
print(id(list))

bar(list)
print(list)
print(id(list))

Why can't I reassign a list (passed as a paramater) in a function?

1 Answers1