Having read this
https://dlang.org/spec/template.html#auto-ref-parameters
I tried to do something like this
// Code starts here
void main()
{
initStruct iSb;
iSb.var = 3;
A b = A(iSb);
assert(*b.myVar == 3); // this works
iSb.var = 4;
assert(*b.myVar == 4); // as expected
b = A(initStruct(5)); // how does
assert(*b.myVar == 5); // this work?
}
struct A
{
@disable this();
size_t* myVar;
this()(auto ref initStruct iS) @nogc
{
import core.stdc.stdio;
__traits(isRef, iS) ? printf("ref case\n") : printf("value
case");
myVar = &iS.var;
/* // This treatment is not needed?
if(__traits(isRef, iS))
{
myVar = &iS.var;
}
else
{
myVar = new size_t(iS.var);
}
*/
}
}
struct initStruct
{
size_t var;
}
// Code ends here
All asserts pass. But the question is how it is possible to avoid
the allocation of memory for the member var of the struct A in
the second case. Is the input remains somewhere and I'm not aware
of this?
By the way, I find the fact very cool. I'm just wondering,
whether I'm doing something unsecure...
