no-arg constructor for structs (again)

[monarch_dodra]

On Wednesday, 19 September 2012 at 12:31:08 UTC, Maxim Fomin 
wrote:
> On Wednesday, 19 September 2012 at 11:51:13 UTC, monarch_dodra 
> wrote:
>> The biggest issue with not having a no-arg constructor can 
>> easilly be seen if you have ever worked with a "Reference 
>> Semantic" semantic struct: A struct that has a pointer to a 
>> payload. Basically, a class, but without the inherited Object 
>> polymorphism.
>
> This means that you still have a class object. What is design 
> behind inserting class into the structure for the sake of 
> escaping from classes?
>

That's not the point at all. For starters, the "Payload" is 
another struct, NOT a class wrapped in a struct.

As for why we aren't using a class to begin with? First, because 
a class wraps much more than we want: polymorphism, adherence to 
a base "Object Type", virtual opEquals, RTTI...

But mostly, because the object we manipulate is a struct and has 
always been a struct. It uses reference semantics, but is in dire 
need of a an initialization to default.

On Wednesday, 19 September 2012 at 14:09:10 UTC, deadalnix wrote:
> Le 19/09/2012 15:24, Timon Gehr a écrit :
>> I don't think making the use of optional parens affect 
>> semantics is an
>> idea worth following.
>
> I have to agree with that.
>
> However, argument-less constructor is something required for 
> struct. The problem is raised on a regular basis on this 
> newsgroup, and some solution already have been proposed.
>
> As discussed earlier in the reference thread, the compiler will 
> have to track down initialization at some point. A struct with 
> an argument-less constructor which isn't initialized must be an 
> error. This will avoid the () semantic dichotomy while solving 
> that problem.
Would you happen to have some links to those proposed solutions, 
or reword them here for us?