On Saturday, 24 July 2021 at 19:39:02 UTC, Alexey wrote:
On Saturday, 24 July 2021 at 18:10:07 UTC, Alexey wrote:
I've tried to use ```typeof(t) is cast(t)null```, but compiler
exits with error and so this can't be used for checking this
issue.
The goal I with to achieve by this check - is to use template
and to assign value to variable basing on it's ability to
accept null as a value.
currently I ended up using ```__traits(compiles,
cast(T1)null)``` for this check. but don't know is this really
semantically correct.
There are probably better ways. However, this seems to work:
```d
import std;
enum canBeSetToNull(T) = __traits(compiles,(T.init is null));
interface I1
{
}
class C1 : I1
{
}
struct S1
{
}
struct S2
{
int a=1;
}
void main()
{
auto c1 = new C1;
I1 i1 = c1;
auto s1 = S1();
auto s2 = S2();
static assert(canBeSetToNull!(typeof(c1)));
static assert(canBeSetToNull!(typeof(i1)));
static assert(!canBeSetToNull!(typeof(s1)));
static assert(!canBeSetToNull!(typeof(s2)));
static assert(!canBeSetToNull!(int));
static assert(canBeSetToNull!(int*));
}```