'new' class method

[KennyTM~]

Benji Smith wrote:
> Bill Baxter wrote:
>> On Fri, Oct 24, 2008 at 3:01 PM, Benji Smith 
>> <dlanguage at benjismith.net> wrote:
>>> Why not just introduce "heap" and "stack" keywords, and say it directly?
>>
>> Did you see my subsequent proposal?  I'm actually quite fond of it.
>> But no one has responded to it.  :-(  [Bill cry's himself a silent
>> tear.]
> 
> You mean the one where you suggested this?
> 
>   auto a = Class();  // heap   (default)
>   auto a = Struct(); // stack   (default)
> 
>   auto a = Class.new(stack)(); // stack
>   auto a = Struct.new(stack)(); // stack
> 
>   auto a = Class.new(heap)(); // heap
>   auto a = Struct.new(heap)(); // heap
> 
 >   void *addr;
 >   auto a = Class.new(addr)(); // placement
 >   auto a = Struct.new(addr)(); // placement
 >

I strongly *oppose* using stack and heap as keywords because there are 
also (partly irrelevant) data structures called stack and heap, even 
though according to the guideline these class/structs should be named 
Stack and Heap.

And I think we can include the meaning that “scope” attribute always 
allocate on stack (Currently 4 conditions need to be met for so), but 
I'm afraid this may break something (otherwise the other 3 conditions 
won't be there?). Maybe some experts can comment on this?

(Ref: http://www.digitalmars.com/d/2.0/memory.html#stackclass)
(Oh, BTW, please fix bug #1521 for clarification.)

And I suggest keeping the “new” syntax for heap ("return a pointer") 
allocation. So,

auto c = Class(...);   // default on heap
auto s = Struct(...);  // default on stack (compatible with current syntax)

scope c = Class(...);  // on stack
scope s = Struct(...); // on stack (compatible with current syntax)

auto c = new Class(...);  // on heap (compatible with current syntax)
auto s = new Struct(...); // on heap (compatible with current syntax)

auto c = new(...) Class(...);  // placement (compatible with current syntax)
auto s = new(...) Struct(...); // placement (compatible with current 
syntax?)


/* if you want symmetry, do it like this:

new c = Class(...);
new(...) c = Class(...);

kinda strange for me. */

These will cause minimum change while eliminating the “new” for most 
cases. This won't free the “new” keyword though.

> Yeah! I noticed it. And I like it. In fact, I thought to myself "that's 
> almost the same as my idea". Generally, I'm not a fan of the consecutive 
> sequence of parentheses (especially that templates already make for 
> double parens; I can't imagine I'd want triple parens for a templatized 
> consttructor call).
> 
> For non-template chained calls, I'm not quite sure which I prefer:
> 
>   auto a = Foo.new(heap)(Bar.new(stack)());
> 
>   auto a = on(heap) Foo(on(stack) Bar());
> 
>> New is already a keyword meaning allocation/construction in D, Java,
>> C++ and maybe C#?  So anyone familiar with those will know right away
>> that "new" probably has something to do with construction.  So the
>> question is why wouldn't you use "new"?
> 
> Well, in Java and C#, objects can *only* be allocated on the heap, and 
> structs can *only* be allocated on the stack (unless they're members of 
> an object, or if they're in an array).
> 
> To me, "new" is a great word for "allocate, and then invoke the 
> constructor", but it doesn't have anything to do with *HEAP* allocation, 
> per se.
> 
> And then I thought to myself "for chrissakes, if you want the heap or 
> the stack, why not ask for it by name?"
> 
> --benji