Bartosz Milewski seems to like D more than C++ now :)

[QAston]

On Thursday, 19 September 2013 at 22:46:09 UTC, Andrei 
Alexandrescu wrote:
> On 9/19/13 3:18 PM, Szymon Gatner wrote:
>> I had similar thoughts when watching GoingNaive 2013:
>> http://bartoszmilewski.com/2013/09/19/edward-chands/
>
> Nice piece.
>
>> I was more and more scared with every talk and now I am 
>> valualizing my
>> polymorphic types a'la Sean Parent
>
> That I think is sketchy advice.
>
>
> Andrei

What Sean Parent does in his value semantics talk is basically an 
interface adapter for a struct, wrapped in a struct providing 
implicit conversions.

By using structs by default and adapting them to interfaces as 
needed you get to have the smallest possible overhead on a single 
function call - either no virtual dispatch or 1 virtual dispatch. 
When writing adapters to interfaces you get 2 or more.

The other benefit is that approach is reducing dependencies you 
need to know about when you use the wrapper type - the approach 
would not work in D due to lack of argument dependent lookup so 
you need to write the adapter type (for a particular type you 
want to convert) yourself anyways. And I think it's better that 
way.

In the end the whole thing is just adapter design pattern applied 
to C++.