On 5/4/20 2:47 AM, Olivier Pisano wrote:
On Monday, 4 May 2020 at 09:20:06 UTC, Ali Çehreli wrote:
On 4/30/20 10:04 AM, Ben Jones wrote:> On Thursday, 30 April 2020 at
16:55:36 UTC, Robert M. Münch wrote:
> I think you want to use scope rather than auto which will put
the class
> on the stack and call its destructor:
> https://dlang.org/spec/attribute.html#scope
That is correct about calling the destructor but the object would
still be allocated with 'new', hence be on the heap. There is also
library feature 'scoped', which places the object on the stack:
https://dlang.org/phobos/std_typecons.html#scoped
Ali
https://godbolt.org/z/SEVsp5
My ASM skills are pretty limited, but it seems to me that the call to
_d_allocclass is omitted when using scope. At least with LDC and GDC.
Am I missing something ?
I stand corrected.
'scope's running the destructor was news to me, so I tested with a
writeln example where the messages changed order depending on whether
'scope' was replaced with 'auto' or not:
import std.stdio;
class C {
~this() {
writeln("~this");
}
}
void foo() {
scope c = new C(); // <-- here
}
void main() {
foo();
writeln("foo returned");
}
Now it's news to me that 'new' does not allocate on the heap when
'scope' is used. I'm not sure I'm comfortable with it but that's true.
Is this unique? Otherwise, 'new' always allocates on the heap, no?
I added the following three lines to the end of foo() too see (without
needing to look at assembly) that the 'scope' and 'auto' class objects
are allocated on different memory regions (by taking object addresses as
proof :) ):
writeln(cast(void*)c);
auto c2 = new C();
writeln(cast(void*)c2);
Ali
