Re: [boost] Formal review for QVM

Subject: Re: [boost] Formal review for QVM
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2015-12-14 17:57:14

On Mon, Dec 14, 2015 at 1:12 PM, Agustín K-ballo Bergé <
kaballo86_at_[hidden]> wrote:

> On 12/14/2015 5:53 PM, Emil Dotchevski wrote:
>
>> On Mon, Dec 14, 2015 at 4:46 AM, Agustín K-ballo Bergé <
>>
> if the compiler says there is an error here because `normalized` needs a
>>> default constructor, I'm gonna start suspecting something wrong is going
>>> on
>>> with the library. This is what I would naively expect `normalized` to be
>>> doing:
>>>
>>>     template <typename Vec>
>>>     Vec normalized(Vec v) {
>>>       return v /= length(v);
>>>     }
>>>
>>
>> It can't be implemented that way because the type of the argument might
>> not
>> be copyable.
>>
>
> Does this mean that the library explicitly supports movable-only types?
> That's somewhat unexpected, given that the library requires all type
> information necessary for embedded storage, but it's not a bad thing. It
> would be good to add this information to the reference documentation.

QVM is neutral wrt move semantics but views are non-copyable and
non-movable because copy or move semantics would require a temporary
object, which QVM views are carefully designed to avoid. You can assign to
a view and it will convert to any compatible type, but you can't copy or
move it. That's why you can chain views up with no overhead: any operation
on a view or multiple chained views works with the original object, no
other objects are created.

Emil