It does make sense if you realize that it is also used for fields and that a.!b.c = d is different than a.b.!c = d. The first makes a copy of the object at a.b

It does make sense if you realize that it is also used for fields and that a.!b.c = d is different than a.b.!c = d. The first makes a copy of the object at a.b before assigning a new value to its field c.