# [Tutor] function with multiple checks

Brian Jones bkjones at gmail.com
Mon Sep 27 17:50:56 CEST 2010

```On Mon, Sep 27, 2010 at 11:43 AM, Brian Jones <bkjones at gmail.com> wrote:

>
>
> On Mon, Sep 27, 2010 at 11:09 AM, Tim Miller <tim at lashni.net> wrote:
>
>> I've got a small function that I'm using to check whether a password is of
>> a certain length and contains mixed case, numbers and punctuation.
>>
>> Originally I was using multiple "if re.search" for the patterns but it
>> looked terrible so I've read up on list comprehensions and it's slightly
>> improved. I just can't escape the feeling that there's a more elegant way to
>> do this that I'm missing.
>>
>> I've been looking through all the python stuff that I thought might be
>> relevant (lambda, map, filter, set, frozenset, etc) but nothing has come
>> together. Just wondering if anyone has suggested reading material for
>> alternate ways they'd handle this code.
>>
>> CODE:
>>
>> from string import ascii_lowercase, ascii_uppercase, digits, punctuation
>>
>>
>>    """Checks password for sufficient complexity."""
>>    if len(password) < 12:
>>        return False
>>    if len([c for c in password if c in punctuation]) == 0:
>>        return False
>>    if len([c for c in password if c in digits]) == 0:
>>        return False
>>    if len([c for c in password if c in ascii_uppercase]) == 0:
>>        return False
>>    if len([c for c in password if c in ascii_lowercase]) == 0:
>>        return False
>>    return True
>>
>

d = [digits, punctuation, ascii_uppercase, ascii_lowercase]
s = 'asdf1234A'
for c in d:
if not [x for x in s if x in c]:
print x, ' not in ', c

Just a quick hack, but you get the idea. It breaks when you want different
numbers of characters from the different lists in the password.

>
>
> You can probably make other optimizations, but just to start, you can get
> rid of 'len' and '== 0':
>
> if not [c for c in password if c in ascii_lowercase]:
>    return False
>
> will return False if there are no lowercase characters. An empty list
> evaluates to False. With that in mind, you could just 'return [c for c in
> password if c in ascii_lowercase]' if the calling code is written to handle
> it.
>
>
>
>
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>
>
>
> --
> Brian K. Jones
> My Blog          http://www.protocolostomy.com
>

--
Brian K. Jones
My Blog          http://www.protocolostomy.com