列表理解中的格式打印问题

Question

Hi all im trying to use list comprehension and some filtering to clean up a list. For some reason (that alludes me) The filtering wont work as expected, ive double checked my syntax and triple checked it im almost positive its correct.

Im expecting an output similar to this:

DOMAINNAME\\USERNAME

What im getting is this

C:\python27\filename
DOMAINNAME\USERNAME

The above suggests to me that the .format type formatting is not working in my below code.

def tllocal(domain):
    try:
        out = subprocess.check_output(["tasklist", "/V", "/FO", "List", "/FI", "USERNAME eq {0}\*" .format(domain)])
        users = [item for item in out.split() if "{0}" and "\\" in item .format(domain)]
        sortedl = set(users)
        print sortedl
        for name in sortedl:   
           print name
    except CalledProcessError as e:
        print(e.returncode)
    return sortedl

I believe it is this line causing the problem.

users = [item for item in out.split() if "{0}" and "\\\\" in item .format(domain)]

Any help would be appreciated.

Answer 1

You are correct, that is incorrect. This expression

if "{0}" and "\\" in item .format(domain)

is parsed as:

(if '{0}') and ("\\" in item .format(domain))

Which is always True since the string literal '{0}' is always true.

The correct way of writing the above is all :

[item for item in out.split() if all(x in item for x in (domain, '\\'))]

Or simply and , since you only have two elements:

[item for item in out.split() if domain in item and '\\' in item]