Why is there no list.clear() method in python?

Question

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Why is there no list.clear() method in python? I\'ve found several questions here that say the correct way to do it is one of the followin

Answer 1

I can't answer to the why; but there absolutely should be one, so different types of objects can be cleared with the same interface.

An obvious, simple example:

def process_and_clear_requests(reqs):
    for r in reqs:
        do_req(r)
    reqs.clear()

This only requires that the object support iteration, and that it support clear(). If lists had a clear() method, this could accept a list or set equally. Instead, since sets and lists have a different API for deleting their contents, that doesn't work; you end up with an unnecessarily ugly hack, like:

def process_and_clear_requests(reqs):
    for r in reqs:
        do_req(r)
    if getattr(reqs, "clear"):
        reqs.clear()
    else:
        del reqs[:]

As far as I'm concerned, using del obj[:] or obj[:] = [] are just unpleasant, unintuitive hacks to work around the fact that list is missing clear().

This is taking "reducing redundancy" to a fault, where it damages the consistency of the language, which is even more important.

As to which you should use, I'd recommend del obj[:]. I think it's easier to implement for non-list-like objects.