Why there are no 'physical' object variables (only references)?

[Reiner Pope]

BCS wrote:
> Lionello Lunesu wrote:
>> BCS wrote:
>>
>>> Sean Kelly wrote:
>>>
>>>> Kristian wrote:
>>>>
>>>>>
>>>>> Hmm, what if structures could have interfaces and 
>>>>> constructors/destructors... and what the heck, inheritance too? 
>>>>> Hehheh, this way we would have 'physical classes' for local use and 
>>>>> 'reference classes' for global use.
>>>>
>>>>
>>>>
>>>> It will never happen :-)  Though ctor support would be nice, at the 
>>>> very least.  That would simplify initialization and eliminate the 
>>>> need for the static opCall trick.
>>>>
>>>>
>>>> Sean
>>>
>>>
>>> There is no technical reason struct (or anything that can produce a 
>>> delegate) can't do interfaces. Inheritance on the other hand... I 
>>> hope that never happens.
>>
>>
>> Wouldn't it add a hidden __vtbl to your struct and thereby increasing 
>> its size?
>>
>> L.
> No, because the type of a struct is always known, the required value for 
> the interface's function table can be found at compile time and all that 
> is needed is to attach it to a reference to the struct.
I don't understand you. How would it work?

Suppose you had this code:

interface Foo
{
	int foo();
}

struct Bar : Foo
{
	int foo() { ... }
	...
}

void calc(Foo f) { ... }

How can calc know the type of every struct it is passed unless a 
separate version of calc is generated for every type (in which case it 
is just a template)?

Cheers,

Reiner