Auto syntax revisited

[Regan Heath]

On Mon, 20 Feb 2006 21:23:26 +0100, Fredrik Olsson <peylow at gmail.com>  
wrote:
> After some discussion on #d I though why not put my thoughts into more  
> permanent writing.
>
> Keyword auto is used for two reasons; implicit type and making sure the  
> object is destroyed when going out of scope. I suggest a new keyword for  
> the latter: local.
>
> local auto foo = new Bar();
>
> Why? First of auto is only used for the implicit type, so no confusion.  
>   The keyword local in itself describes pretty to the point what is  
> supposed to happen with the variable. And nothing is said about the  
> stack, so we are future proof if in the future we would like to also  
> have:
>
> local auto foo = Bar();
>
> Where Bar(); is a function returning an Object, but we still want the  
> object to be destructed when going out of this scope. The implementation  
> is quite different as the Object would need to be on heap, but the  
> syntax is the same. So local would indicate what should be done (destroy  
> when out of scope), not how it should be done (allocate on stack or  
> whatever).
>
> Even this could be possible, without syntax changes:
> {
>    local Foo bar;
>    // some code
>    Baz(bar); // Jupp Baz have a inout parameter returning an object.
> } // And bar is still destroyed if set to something here...

I thought the plan was to deprecate "auto" WRT declaring stack based auto  
destructed class instances, resulting in:

class A {}

A a = new A(); //heap alloc
A a = A();     //stack alloc, destruct at scope exit

So, "auto" would only mean "automatic type determination":

auto a = new A(); //heap alloc, 'a' is of type reference to 'A'
auto a = A();     //stack alloc, destruct at scope exit, 'a' is of type  
reference to 'A'

Regan