[boost] Re: [ANN] Phoenix-2 Preview

From: Joel (joel_at_[hidden])
Date: 2004-11-26 20:48:37

David Abrahams wrote:
> Joel de Guzman <joel_at_[hidden]> writes:
> 
> 
>>Hi. Here's a preview of Phoenix V2. This will probably be the last
>>release of the library. Phoenix V2 will be the basis of the Phoenix
>>and Boost.Lambda merger.
> 
> 
> 
>   If these basic rules are not followed, the result is either in
>   error, or is immediately evaluated. Some examples:
> 
>     var(x) = 123 // good (lazy)
>     x = 123 // oops (immediate)
>     var(x)[0] // good (lazy)
>     x[0] // oops (immediate)
>     var(x)[var(i)] // good (lazy)
>     x[var(i)] // bad and illegal (x is not a phoenix primitive or composite)
>     var(x[var(i)]) // bad and illegal (x is not a phoenix primitive or composite)
> 
> I would avoid attaching value judgements, and in this case,
> vertically align the comments:
> 
>     x = 123          // immediate
>     var(x) = 123     // lazy
> 
>     x[0]             // immediate
>     var(x)[0]        // lazy
> 
>     var(x)[var(i)]   // lazy
>     x[var(i)]        // illegal (x is not a phoenix primitive or composite)
>     var(x[var(i)])   // illegal (x is not a phoenix primitive or composite)

Done. Thanks!

> And this leaves me wondering what about:
> 
>     var(x)[i]

Lazy. Equivalent to:

     var(x)[val(i)]

Added to the examples.

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net