On Friday, 13 August 2021 at 17:19:43 UTC, H. S. Teoh wrote:
On Fri, Aug 13, 2021 at 05:11:50PM +0000, Rekel via
Digitalmars-d-learn wrote: [...]
For anyone more experienced with C, I'm not well known with
references but are those semantically similar to the idea of
using a type at a predefined location?
References are essentially pointers under the hood. The
difference is that at the language level they are treated as
aliases to the original variable, and are therefore guaranteed
to be non-null.
Note that in D `ref` is not a type constructor but a storage
qualifier, so you cannot declare a reference variable, you can
only get one if you pass a variable to a function that takes it
by ref.
T
Thanks for all the replies.
I had a look at emplace but it does not seem to do exactly what I
have in mind.
What I had in mind would have the following behaviour. Suppose we
optionally
allow "in <exp> before the semi-colon at the end of a
declaration. With the following semantics
T x;
T y in &x;
assert(x==y);
assert(&x==&y);
Note that I am not suggesting that the syntax I wrote is what
exists or should exist. I think what I am suggesting is not the
same as say implicitly dereferenced pointers. If you think of the
underlying machine, variables are aliases for locations in memory
where values are stored, and what I am asking is whether it is
possible to alias an arbitrary location (provided it contains the
correct type.) (I guess what I am saying is only conceptually
true variables might end up in registers, but from the point of
view of the language it is true since if v is a variable, then &v
is defined to be its address.)
This would allow things like:
Given:
struct S
{
int x;
int y;
}
You can write:
S s = S(1,2) in new S;
ending up with s being defined on the heap.
Anyway I hope it is clearer what I mean. Is it possible to do
this in d?
