Re: struct on heap with std.experimental.allocator
On Tuesday, 7 June 2016 at 15:43:34 UTC, Adam D. Ruppe wrote: On Tuesday, 7 June 2016 at 15:39:59 UTC, jmh530 wrote: My sense is that putting it on the GC heap gives the struct reference semantics. It doesn't matter what heap it is on, you are just using a pointer here. Struct pointers in D will automatically dereference with a.x, so no need for the * there (in most cases), and assigning it to another pointer of course still points to the same object, so it will affect both. If you want a copy, you can use a special method to allocate a new one or use auto a = *b; which will copy it to the stack. Thanks for the reply!
Re: struct on heap with std.experimental.allocator
On Tuesday, 7 June 2016 at 15:39:59 UTC, jmh530 wrote: My sense is that putting it on the GC heap gives the struct reference semantics. It doesn't matter what heap it is on, you are just using a pointer here. Struct pointers in D will automatically dereference with a.x, so no need for the * there (in most cases), and assigning it to another pointer of course still points to the same object, so it will affect both. If you want a copy, you can use a special method to allocate a new one or use auto a = *b; which will copy it to the stack.
struct on heap with std.experimental.allocator
I modified one of the first examples from
std.experimental.allocator to put a struct on the heap (below).
My sense is that putting it on the GC heap gives the struct
reference semantics. I was struck by two things. First, I didn't
have to use (*a).x, I could just use a.x. Also, when I assign a
struct object to another instance, changes in the new one also
effect the original.
import std.experimental.allocator;
struct A
{
int x;
}
void main()
{
A* a = theAllocator.make!A(42);
assert((*a).x == 42);
assert(a.x == 42);
auto b = a;
assert(b.x == 42);
++b.x;
assert(b.x == 43);
assert(a.x == 43);
}
