only_readable_once_list.py

"""
Attention Agent.

The White House is currently developing a mobile app that it can use to issue instructions to its undercover agents.

Part of the functionality of this app is to have messages that can be read only once, and are then destroyed.

As our best undercover developer, we need you to implement a SecureList class that will deliver this functionality.

Behaviour different to the traditional list is outlined below:

Accessing an item at any index should delete the item at that index eg:
messages=SecureList([1,2,3,4])
print messages[1]  # prints 2
print messages     # prints [1,3,4]
Printing the whole list should clear the whole list eg:
messages=SecureList([1,2,3,4])
print messages     # prints [1,2,3,4]
print messages     # prints []
Viewing the representation of the list should also clear the list eg:
messages=SecureList([1,2,3,4])
print "my messages are: %r."%messages     # prints "my messages are: [1,2,3,4].
print messages     # prints []
To complete this kata you need to be able to define a class that implements __getitem__(), __str__(), __repr__(), and
possibly __len__().

Good luck Agent.
"""


class SecureList():
    def __init__(self, arr):
        self.arr = [item for item in arr]

    def __getitem__(self, key):
        val = self.arr[key]
        self.arr.pop(key)
        return val

    def __str__(self):
        arr = self.arr
        self.arr = []
        return str(arr)

    def __repr__(self):
        arr = self.arr
        self.arr = []
        return str(arr)

    def __len__(self):
        return len(self.arr)