From: Sebastian Hungerecker <sepp2k@...>
Date: 2009-04-18T00:25:37+09:00
Subject: Re: simple (?) question regarding the "&&" and "and" operators

Philip Müller wrote:
> a and b
>
> => b
>
> ?
>
> I would expect it to return true.


The pseudo-code for and basically looks like this:
a and b =
  if a: b
  else: a
This means that if a or b evaluate to a something that counts as false, then 
the whole expression will also evaluate to something that counts as false. 
And if neither of them do, then the whole expression will evaluate to 
something that counts as true. So for if-conditions etc. the expression will 
work as expected.
The reason that it returns a/b and not true/false is that
a) there are very few cases where you need the value to be an explicit boolean
b) there are quite a few cases where returning a/b is more meaningful and/or 
useful than just returning true/false (though that's more the case for "or" 
than "end". Example: foo = ARGV[0] or default_value).

HTH,
Sebastian