On 04.11.2012 13:58, Dan wrote:
This may be a manifestation of bug 1528. In the code below how can I
heap allocate a default S? I can't seem to get a call to work.
In general structs are stack objects, but is there any problem with
using the heap to get one?
No, you can get one, but op new returns a pointer to the struct on the heap.
Furthermore if you define your own constructor, your struct will not
have an no arg constructor anymore.
----------------------------------
import std.stdio;
import std.traits;
struct T { int t; }
struct S {
T[] ts;
this(U)(U[] values...) if (isImplicitlyConvertible!(U, T)) {
foreach (value; values) {
ts ~= value;
}
}
this(this) {
ts = ts.dup;
}
}
void main() {
// S *sp3 = new S; // no no-aro constructor
// Same - here but also 'no constructor for S'
>
// S sp3 = new S([]); // you forgot the *.
> // this works:
> // S* sp3 = new S(cast(T[])[]);
Sadly you have to cast, because typeof([]) is void[]. Alternatively you
could define an constructor that takes void[] but insists of the
argument being empty.
// Same
// S sp3 = new S(); // no no-arg constructor and no *
}
struct S {
T[] ts;
this(U)(U[] values...)
if (isImplicitlyConvertible!(U, T) &&
!is(U == void))
{
foreach (value; values) {
ts ~= value;
}
}
// extra constructor for []
this(U)(U[] values) if(is(U == void))
{
enforce(values.length == 0);
}
this(this) {
ts = ts.dup;
}
}
// works now too.
S* s = new S([]);
