Re: [boost] [convert] are you mixing default_value and error_value?

Subject: Re: [boost] [convert] are you mixing default_value and error_value?
From: Vladimir Batov (batov_at_[hidden])
Date: 2009-07-09 04:38:40

> From: "Vicente Botet Escriba" <vicente.botet_at_[hidden]>
> ...
>> Do we need to give an initial value just for conversion to work at
>> all, or is it only needed as a return in the error case?
>>
>> Tony
>
> It is needed for both usages: the initial value when the class is not
> default constructible, and the error value when we want this value to be
> returned when failure. Now we can not have an exception for the conversion
> to a class that is not default constructible because when we give a 
> default
> value it is also interpreted as the error value. As I said we are mixing
> both concepts, which is not good, as both are orthogonal.

The is only *one* value provided -- a conversion-failure value. It happens 
to be used internally for some initialization (for std::stream-based 
conversions). It's an internal implementation matter and not guaranteed to 
be that way. What do we achieve by stressing it out?

V.