[Tutor] True and 1 [was Re: use of the newer dict types]

[Alan Gauld]

On 27/07/13 20:17, Jim Mooney wrote:

> Since I admitted to still being a bit confused, I though it out, and:
>
>>>> [[[[[L]]]]] == L
> True
>
> False propagates outward, since each containing bracket also contains
> an empty object.


Its not that false propagates out, it's how Python does a comparison of 
lists. The rules for equality are what matter here not the rules of 
boolean conversion.

comparison operations return -1, 0 or 1.
The boolean conversion of that result is effectively the inverse of the 
return value - ie 0 implies equality is true, -1 or 1 implies False.

Try:

 >>> cmp([L],L)

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/