Re: Confused about referencing in D

[Adam D. Ruppe via Digitalmars-d-learn]

On Thursday, 14 July 2016 at 06:23:15 UTC, Gorge Jingale wrote:
I think that the assignment in the first case is not assigning 
the reference returned by auto ref GetValue().



`ref` in D is shallow, it only applies to the thing it is 
specifically on and is lost across assignments. Once you assign a 
ref to a new variable, it isn't ref anymore.



I am expecting it to work like a pointer,


If you need a pointer, use a pointer! ref is a different thing.

Re: Confused about referencing in D

[kink via Digitalmars-d-learn]

On Thursday, 14 July 2016 at 06:23:15 UTC, Gorge Jingale wrote:
I think that the assignment in the first case is not assigning 
the reference returned by auto ref GetValue().


Yep. There's no such thing as C++ `auto& val = GetValue()` in D. 
You'd have to use a pointer instead: `auto pVal = &GetValue()`.

Re: Confused about referencing in D

[rikki cattermole via Digitalmars-d-learn]

On 14/07/2016 6:23 PM, Gorge Jingale wrote:

I'm pretty confused why the following code doesn't work as expected.

GetValue is a struct.

  auto value = GetValue();
  memcpy(&value, &val, Val.sizeof);

But if I plug in value direct to memset it works!!

  memcpy(&GetValue(), &val, Val.sizeof);

GetValue returns memory to stick a value in and the memcpy is copying it
over. It is very confusing logic. Should I not expect the two cases two
be identical?

I think that the assignment in the first case is not assigning the
reference returned by auto ref GetValue().

I am expecting it to work like a pointer,

  void* value = &GetValue();
  memcpy(value, &val, Val.sizeof);

so to speak but it works more like

S value;
value = GetValue();
memcpy(&value, &val, Val.sizeof);

which copies the data to the memory created for value and not the one
returned by GetValue.


Please provide the definitions of GetValue and Val.