Re: [boost] [optional] std::tr2::optional

Subject: Re: [boost] [optional] std::tr2::optional
From: Robert Ramey (ramey_at_[hidden])
Date: 2011-11-29 00:43:25

Robert Ramey wrote:
> Matt Chambers wrote:
>> On 11/28/2011 6:05 PM, Dave Abrahams wrote:
>>> on Fri Nov 18 2011, paul Fultz<pfultz2-AT-yahoo.com>  wrote:
>>>>> I provide a list of
>>>>> modifications that I could think of. What is your opinion?
>>>> This is more of an addition to your list, but I think adding
>>>>
>>>> the | operator for getting the optional value or a default value
>>>> would be nice. For example:
>>>>
>>>> optional<double>  safe_sqrt(double x)
>>>> {
>>>>      if (x<  0) return none;
>>>>      else return sqrt(x);
>>>> }
>>>>
>>>> double x = safe_sqrt(4) | 0; //x = 4
>>>> double y = safe_sqrt(-1) | 0; //y = 0
>>>>
>>>> I dont know if this is possible for tr2, but would be really nice
>>>> addition in the future. Especially, since a lot of times i just
>>>> want a default value if the optional value doesn't exist.
>>> +1
>> +sqrt(4)
>
> -1
>
> since we're all chiming in - I hate ideas like this.  Silently giving
> a seemingly valid answer to an invalid question just hides a bug
> and makes it harder to find.  It's a big source of problems with
> much component type software.

Hmmm - have just read this back, I guessing I'm objecting more
to the example than I am to the suggestion itself.  I really havn't
thought enought about the suggestion itself to have a strong
opinion.

Robert Ramey
>
> Robert Ramey
>
>>
>> _______________________________________________
>> Unsubscribe & other changes:
>> http://lists.boost.org/mailman/listinfo.cgi/boost
>
>
>
>
> _______________________________________________
> Unsubscribe & other changes:
> http://lists.boost.org/mailman/listinfo.cgi/boost