Re: [boost] Interest for a perl6-like-junctions-class?

From: David Abrahams (dave_at_[hidden])
Date: 2005-08-10 12:51:07

Rob Stewart <stewart_at_[hidden]> writes:

> I just took a look at my implementation of all and each.  At
> least in my latest version, it's worse than you describe.  They
> are identical.  Regardless of how I've implemented them, these
> are the intended semantics:
>
>    all: all of the values must match *the same* other value
>
>    each: all of the values must match *some* other value
>
> Thus, all_of({1, 2, 3}) < any_of({3, 4}) means:
>
>    1 < 3: true
>    2 < 3: true
>    3 < 3: false
>    1 < 4: true
>    2 < 4: true
>    3 < 4: true
>    result: true
>
> But, each_of({1, 2, 3}) < any_of({3, 4}) means:
>
>    1 < 3: true
>    2 < 3: true
>    3 < 3: false
>    3 < 4: true
>    result: true

IMO that's terribly confusing.  The first one should be 

  all_of({1, 2, 3}) < one_of({3, 4})    

And the second one should be 

  all_of({1, 2, 3}) < any_of({3, 4})    

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com