[Tutor] function with multiple checks

[Tim Miller]

On 28/09/10 01:46, Jerry Hill wrote:
> The way you've written it obviously works fine.  That being said, I'd
> probably do something like this:
>
> from string import ascii_lowercase, ascii_uppercase, digits, punctuation
>
> def complex_password(password):
>      '''Checks to make sure a password is complex'''
>      checks = [
>          lambda p: len(p)>  12,
>          lambda p: any(c in punctuation for c in p),
>          lambda p: any(c in digits for c in p),
>          lambda p: any(c in ascii_uppercase for c in p),
>          lambda p: any(c in ascii_lowercase for c in p),
>          ]
>
>      return all(check(password) for check in checks)
>
> if __name__ == '__main__':
>      passwords = ['password', 'Password1234567', 'Password1.234567']
>      for password in passwords:
>          print password, complex_password(password)
>
>
> In the complex_password function, I create a list of tests, each of
> which is a function that returns either true or false.  In this case I
> used lambdas to create the function objects, since all the tests
> easily fit on a single line, but it would be fine to define a function
> elsewhere and use it in the list if you had more complicated checks to
> do.
>
> all() is a built in function that returns True if all of the elements
> in an iterable are true (or the iterable is empty), and otherwise
> returns False.  That seems like an ideal way to execute a bunch of
> tests and return True if all of them pass, and otherwise return false.
>   In this case, the iterable is a generator expression that evaluates
> each of the rules with the supplied password.
>
> any() is similar, but it returns True if any member of the iterable is True.
>
> Looking back at it, I probably should have used longer variable names
> in my rules, which would have made them a bit easier to read.  When I
> was writing them, I was worried about the lines getting too long with
> longer names.  It didn't turn out to be a problem though.
>

After doing a bit more reading and trying out some of the very useful 
suggestions people have made in this thread, I've decided to rework that 
section based on your example.

I was trying to use lambdas to solve this earlier but it's new territory 
for me and I couldn't figure out how to string them together as you've 
done above. The explanation is especially invaluable, thanks.