When is del useful in Python?
Firstly, you can del other things besides local variables
del list_item[4]del dictionary["alpha"]Both of which should be clearly useful. Secondly, using del on a local variable makes the intent clearer. Compare:
del footo
foo = NoneI know in the case of del foo that the intent is to remove the variable from scope. It's not clear that foo = None is doing that. If somebody just assigned foo = None I might think it was dead code. But I instantly know what somebody who codes del foo was trying to do.
There's this part of what del does (from the Python Language Reference):
Deletion of a name removes the binding of that name from the local or global namespace
Assigning None to a name does not remove the binding of the name from the namespace.
(I suppose there could be some debate about whether removing a name binding is actually useful, but that's another question.)
One place I've found del useful is cleaning up extraneous variables in for loops:
for x in some_list: do(x)del xNow you can be sure that x will be undefined if you use it outside the for loop.