Mass Name Generation

We'd first have to generate all the possible names, shuffle them, and then use next (the simplest way) or maintain a current_index and get the name. Note that selecting randomly from the list of all names would be incorrect, as there's a possibility of the name being repeated.

Here's a possible way to do it:

from itertools import product
from random import shuffle
from string import ascii_uppercase

letter_pairs = (''.join(p) for p in product(ascii_uppercase, ascii_uppercase))
numbers = (str(i).zfill(3) for i in range(1000))
names = [l + n for l, n in product(letter_pairs, numbers)]

shuffle(names)
NAMES = iter(names)

class Robot(object):
    def __init__(self):
        self.reset()
    def reset(self):
        self.name = next(NAMES)

The first few lines of the mass name generation uses itertools.product. The resultant code is a simplification of:

letter_pairs = (''.join((l1, l2)) for l1 in ascii_uppercase for l2 in ascii_uppercase)
numbers = (str(i).zfill(3) for i in range(1000))
names = [l + n for l in letter_pairs for n in numbers]

After the name generation, the names are shuffled - using the default seed in the random module (the current timestamp). When the tests reseed random, this has no effect as the names were shuffled before that.

We then set NAMES to the iterable of names, and in reset, set the robot's name to the next(name). If you'd like, read more on iter and next.

Unlike the on the fly approach, this has a relatively short "generation" time, because we're merely giving the next name instead of generating it. However, this has a huge startup memory and time cost, as 676,000 strings have to be calculated and stored. For an approximate calculation, 676,000 strings * 5 characters / string * 1 byte / character gives 3380000 bytes or 3.38 MB of RAM - and that's just the memory aspect of it. Sounds small, but it's relatively very expensive at the beginning.

Thus, this approach is inefficient in cases where only a small number of names are needed and the time to set/reset the robot isn't crucial.