On Thursday, 1 September 2016 at 19:37:25 UTC, Yuxuan Shui wrote:
I just figured out how to store a reference:
@safe:
auto x(ref int a) {
struct A {
ref int xa() { return a; }
}
return A();
}
void main() {
import std.stdio;
int b = 10;
auto a = x(b);
a.xa = 20;
writeln(b); //Prints 20
}
I have no idea if this is a right thing to do. Can someone tell
me if this is idiomatic D, and whether there're any catches to
this method or not?
Thanks.
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.
