CODEWITHSUNDEEP
pythonslicedel
spiderface
spiderface

Reputation: 1135

Python slice with del statement

Why does this:

del a[:]

delete all entries in the list a?

As far as I understand, a[:] returns a copy of a. So shouldn't del a[:] delete the copy of a?

Upvotes: 4

Views: 3437

Answers (1)

Bharel
Bharel

Reputation: 26971

del is a special statement that will check the original value and delete it using the given slice.
It calls __delitem__ on the object and the object itself handles the deletion.

If you're curious regarding the operation happening under the hood, you're welcome to implement the following class and use the del statement with different slices or key references:

class A:
    def __delitem__(self, key):
        print(key)

The test in the interpreter:

>>> a = A()
>>> del a[:]
slice(None, None, None)
>>> del a[2]
2
>>> del a["test"]
test

Upvotes: 4

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