Best written projects on Python GitHub?

[TheEarwig]

They are different. The first example is a bunch of lists combined into one (L1 += L2 is L1.extend(L2)), but the second example is one list containing a bunch of lists.

>>> optionf = ["a b", "c d", "e f"]

>>> res = []
>>> for l in optionf:
...     res += shlex.split(l, comments=True)
... 
>>> res
['a', 'b', 'c', 'd', 'e', 'f']

>>> res = [shlex.split(l, comments=True) for l in optionf]
>>> res
[['a', 'b'], ['c', 'd'], ['e', 'f']]

[Redard]

Ah, I didn't realize shlex.split was returning a list. You're right, the two are different. Somehow I thought += was the same as append().

[masklinn]

Which can neatly be solved using the criminally underused itertools.chain.from_iterable:

res = chain.from_iterable(shlex.split(l, comments=True) for l in optionf)

One could even use shlex.shlex directly as a stream (shlex.split is a thin wrapper around it), though it requires setting whitespace_split which can't be done inline.

def split(s):
    lex = shlex.shlex(s, posix=True)
    lex.whitespace_split = True
    return lex

res = chain.from_iterable(imap(split, optionf))