On 9/1/16 4:38 PM, Yuxuan Shui wrote:
On Thursday, 1 September 2016 at 20:28:03 UTC, Rene Zwanenburg wrote:
On Thursday, 1 September 2016 at 19:37:25 UTC, Yuxuan Shui wrote:
[...]
This will allocate a closure. A struct definition inside a function
has a hidden context / closure pointer, unless it's a static struct.
There is nothing like a ref variable in D. If you want to refer to
something someplace else, use a pointer. You can create a pointer
wrapper which acts like a reference (untested):
auto toRef(ref T value)
{
return Ref!T(&value);
}
struct Ref(T)
{
private T* value;
@property ref T _value() { return *value; }
alias _value this;
}
Note that D's pointer syntax is a bit friendlier than C++'s: the dot
operator works fine on pointers. A good reason to use the Ref wrapper
is to forward arithmetic operations to the wrapped value.
I think my approach is probably better, because I believe (correct me if
I'm wrong): 1) it will never refer to a null object. 2) after DIP1000 is
implemented we will be able to make sure there will be no dangling
reference.
Referring to a null object is not a problem. Your program crashes
ungracefully, but does not corrupt memory. However, in either approach,
it can easily end up being a dangling pointer.
But to refer to a null location is quite easy:
int *foo; // null ptr
auto a = x(*foo);
assert(&a.xa() == null);
Your approach is less desirable because of the closure to point at a
given reference which can be had with just a reference. Needless allocation.
-Steve
