December 20, 2018
On Thursday, 13 December 2018 at 18:29:39 UTC, Adam D. Ruppe wrote:
> The attribute spam is almost longer than the function itself.

I often wished for something like

----
module foo.bar;

default(@safe, pure);

function foo() { } // is annotated with @safe & pure

@deny(pure) // or pure(false) as I suggested a long time ago
function bar() { } // is annotated only with @safe
----

That would IMO lighten the burden.
December 20, 2018
default(attributes..) is no needed. You can already do this by:

pure @safe:
// your code

But what is needed is some way to disable those attributes.  As you mentioned  one way could be done by allowing this:

pure(false)  or pure!false or @disable(pure,@nogc...)

>From implementation point of view it is not hard.  I have already
implemented this before. I have even write some old DIP. But there is new DIP process so someone need to write a new one and need to be able to get it throw new DIP process. And I do not feel I have enough strength to do this right now.

čt 20. 12. 2018 8:50 odesílatel Dgame via Digitalmars-d-announce < digitalmars-d-announce@puremagic.com> napsal:

> On Thursday, 13 December 2018 at 18:29:39 UTC, Adam D. Ruppe wrote:
> > The attribute spam is almost longer than the function itself.
>
> I often wished for something like
>
> ----
> module foo.bar;
>
> default(@safe, pure);
>
> function foo() { } // is annotated with @safe & pure
>
> @deny(pure) // or pure(false) as I suggested a long time ago
> function bar() { } // is annotated only with @safe
> ----
>
> That would IMO lighten the burden.
>


December 20, 2018
On Wednesday, 19 December 2018 at 23:10:34 UTC, Rubn wrote:
> On Wednesday, 19 December 2018 at 19:58:53 UTC, Neia Neutuladh wrote:
>> [...]
>
> To be fair even in c++ this won't be a reference.
>
> int& foo();
> auto a = foo(); // a == int
> auto& a = foo(); // a == int&
>
> So it shouldn't be that surprising.

decltype(auto) a = foo(); // a == int&

And you can explicitly declare `auto&` in C++, which you can't do in D.

December 20, 2018
On 12/19/18 2:58 PM, Neia Neutuladh wrote:
> On Wed, 19 Dec 2018 17:28:01 +0000, Vijay Nayar wrote:
>> Could you please elaborate a little bit more on this?  In the linked
>> program, I had expected that "ref" would return a reference to "a" that
>> would behave similar to a pointer.
> 
> They work like pointers that automatically dereference when assigning to
> the base type.
> 
> Only three things in D can be ref:
> * A function parameter
> * A function return value
> * A foreach variable (since that's either going to be a function return
> value, a function parameter, or a pointer, depending on what you're
> iterating over)
> 
> So when the compiler sees something like:
> 
>      ref int foo();
>      auto a = foo();
> 
> It sees that the type of 'a' has to be the same as the return type of
> 'foo'. Except that's not possible, so it uses the nearest equivalent type:
> int.

I would say it a little bit differently -- the return *type* of foo is int. In D, ref is not part of the type at all.

For example, even when it *could* use ref, it doesn't:

int x;
ref int foo() { return x; }

void bar(Args...)(Args args)
{
   pragma(msg, __traits(isRef, args[0]));
}

bar(foo()); // outputs false at compile time

The storage class is completely separate from the type. Which is different from C++, where it's like a storage class but is really a type constructor, hence Walter's post.

-Steve
December 20, 2018
On Thu, 20 Dec 2018 14:19:33 +0100, Daniel Kozak wrote:
> default(attributes..) is no needed. You can already do this by:
> 
> pure @safe:
> // your code

That doesn't work if you have any member functions, and Walter says it's unlikely that that will ever change, even with a DIP.

default(pure) would be new syntax with no existing code broken.
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