What is the alphanumeric id in a reddit URL?

Question

What is the 7n5lu in the reddit URL

http://www.reddit.com/r/reddit.com/comments/7n5lu/man_can_fly_if_you_watch_one_video_in_2

Answer 1

The reddit source code is available! Here is what I found for generating that string:

def to_base(q, alphabet):
    if q < 0: raise ValueError, "must supply a positive integer"
    l = len(alphabet)
    converted = []
    while q != 0:
        q, r = divmod(q, l)
        converted.insert(0, alphabet[r])
    return "".join(converted) or '0'

def to36(q):
    return to_base(q, '0123456789abcdefghijklmnopqrstuvwxyz')

and elsewhere, under the "Link" class:

@property
def _id36(self):
    return to36(self._id)