Problems with D const ref vs C++ const &

[Piotr Szturmaj]

Jonathan M Davis wrote:
> On Friday, December 10, 2010 14:31:34 Piotr Szturmaj wrote:
>> Craig Black wrote:
>>> In C++ I could to the following:
>>>
>>> Vector3 cross(const Vector3&a, const Vector3&b) { ... }
>>>
>>> and then call it like this:
>>>
>>> Vector3 a, b, c;
>>> a = cross(b, c);
>>> a = cross(b-a, c-a);
>>>
>>> But in D I have to define two functions if I want pass by reference to
>>> work:
>>>
>>> Vector3 cross(ref const Vector3 a, ref const Vector3 b) {...}
>>> Vector3 cross(Vector3 a, Vector3 b) {...}
>>
>> Isn't const for that (without ref)?
>>
>> Vector3 cross(const Vector3 a, const Vector3 b) {...}
>>
>> In this case, compiler should pass const by reference (since it will not
>> change).
>
> The compiler doesn't just make things references. You have to tell it to. If you
> have a const parameter which is a value type, it's just going to be a const
> local variable. It's not going to be a reference to anything no matter what that
> means for efficiency (though structs are supposedly supposed to be cheap to copy).
> Now, if Vector3 were a class, then it's always a reference. But that's because
> it's a reference type.
>
> - Jonathan M Davis

Thank you for your explanations, I'm just learning D2. However, I meant 
something different: passing by reference was not strict ref in my mind, 
but some kind of address passing.
This is done in Pascal/Delphi for more than decade. Variables passed as 
const parameters, are passed by address, to improve efficency, even if 
they're value types. Of course smaller builtin types like 32 bit integer 
doesn't get much advance. Const is supposed to be used with Vector3-like 
structs with floating point coordinates (12 bytes float, 24 bytes 
double), where it's better to not copy. Feel free to read first answer 
to this post:
http://stackoverflow.com/questions/1600991/are-there-any-advantages-in-using-const-parameters-with-an-ordinal-type

Question is, if const parameters works similarly in D2?