Clearing python list with slice operator copy -

i came across following python 2.6 code python

for in elements[:]:     elements.remove(i)

i'm trying figure out reason use syntax clearing list. understand concept of inplace deletion, why not example:

del elements[:]

elements[:] = []

thx !

you must think of python lists 'pointers'.

for example, if declare list so:

elements = [1, 2, 3]

this seen in memory this:

elements → [ ↓, ↓, ↓ ]              1  2  3

so when change element in list doing this:

elements[1] = 4                 4 elements → [ ↓, ↑, ↓ ]              1  2  3

notice how number 2 has no pointer reference 'gone or lost memory' , it's no longer accessible. same happens when re-assign variable itself:

elements[:] = []           [] elements ↑     [ ↓, ↓, ↓ ]                  1  4  3

the key understand here original list 'gone or lost memory' , it's no longer accessible. important key understand slicing:

elements[:] get's pointer (or arrow in illustrations) variable referring to.

so that's why it's same use

del elements[:] (i delete arrow , set new arrow empty list)

elements[:] = [] (i make variable point new empty list, old arrow deleted when dereferenced)

hope helps!

Swift