[boost] Re: [optional]output

From: Joel de Guzman (joel_at_[hidden])
Date: 2005-03-08 22:59:29

David Abrahams wrote:
> "Peter Dimov" <pdimov_at_[hidden]> writes:
> 
> 
>>Gennadiy Rozental wrote:
>>
>>>I believe this version is much less intuitive. optional<T> v is still
>>>value of type T which may or may not be present. Accordingly when we
>>>print it we print the value if it present or print nothing if it not.
>>
>>This isn't very useful. The output cannot be read back, and when printing a 
>>sequence of optionals much of the information is lost. 
> 
> 
> Agreed.  I was going to say that an empty optional should print
> something, but couldn't articulate the reasons.  Thanks.

Perhaps do as the tuples do?

     [123] <- a non-empty optional<int>
     []    <- an empty optional<T>

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