Re: [Boost-users] boost:any/boost::variant for integral/floating type

Subject: Re: [Boost-users] boost:any/boost::variant for integral/floating type
From: Mathieu Malaterre (mathieu.malaterre_at_[hidden])
Date: 2010-06-03 05:22:54

On Tue, Jun 1, 2010 at 4:42 PM, Larry Evans <cppljevans_at_[hidden]> wrote:
> On 06/01/10 08:12, Mathieu Malaterre wrote:
>>
>> Hi,
>>
>>  I am looking at boost::any and boost::variant which seems to be very
>> usefull additions to C++ for building heterogenous containers.
>>  However in my case I need to build something that would be:
>> - type safe
>> - can only contains integral/floating type
>
> [snip]
>>
>> Did I miss anything in boost ? Is boost::variant my best option (when
>> only using fundamental types) ?
>
> Look out for the boost:;variant trap revealed by the post:
>
>  http://article.gmane.org/gmane.comp.lib.boost.user/58791
>
> The problem occurs when one component can be constructed from another
> component. as suggested by this quote from the above post:
>
>> When bool is added to variant, the statement
>> variant = "hello world" ;
>> calls bool constructor.
>>
>
> I think something similar may happen here, but maybe the problem
> can be solved by some order of the bound components.  Maybe putting
> more "stringent" components either first or last.  That way, maybe
> the correct one would be selected when the assignment is made.

Thanks for the warning. My base type are fundamental type, so I should
not suffer from this implicit cast.

Thanks
-- 
Mathieu