Copy Constructor DIP

[RazvanN]

> What's wrong with:
> struct S {
>   this(ref S copyFrom);
> }
>
> That looks like a perfectly good copy constructor declaration 
> ;) I'm just saying, the DIP needs to explain this.

That is actually a valid constructor, according to today's 
compiler. There
might be code out there that uses this syntax for the constructor 
and overnight
it will be turned into a copy constructor.

I agree that the current syntax is lacking. This was Andrei's 
proposition
and I was initially against it, but he said to put it in the DIP 
so that
we can discuss it as a community. Maybe this syntax is better:

@this(ref S a another)

It looks like the c++ copy constructor but the `@` makes it 
different from
a constructor, so we're good. What do you think?

> Right. This is all obvious and intuitive.
> What I'm hearing is that under this proposal, copy constructors 
> and
> assignment operators DO come in pairs (just like in C++), but 
> that's
> not mentioned here in this DIP. Since this proposal will 
> introduce
> that recommended pattern from C++, it may be worth mentioning.

If by "come in pairs" you mean that you can define them both, 
then yes,
that is the case. Will add a paragraph in the DIP to specify this.

You mentioned that it's terrible that the assignment operator
and the copy constructor come in pairs. Why is that? Would you 
rather
have a copy constructor that is used also as an assignment 
operator?