On 7/11/18 8:55 AM, Timoses wrote:
On Tuesday, 10 July 2018 at 18:01:59 UTC, Steven Schveighoffer wrote:
You are overthinking :) inout typically is much easier than you
expect, until you need to create temporary structs or types with inout
members, then it becomes problematic.
https://run.dlang.io/is/kosYuC
I had to put in a static if, because your function doesn't work once
you get down to the array type. See the // fixme comment.
Ok, well that helped a tiny bit for the example.
I'm trying to reproduce the errors from my project. It's starting to get
out of control : D. inout is on a rampage!
https://run.dlang.io/is/5TN7XX
I guess it's the same as for immutable initialization of arrays. I can't
seem to find a proper response to this one..
import std.traits;
struct S
{
int[3] arr;
}
struct SS
{
S s;
}
interface I
{
inout(I) opIndex(size_t idx) inout;
}
class Test(T) : I
{
T member;
this(inout T mem) inout
{
this.member = mem;
}
inout(Test!T) get() inout
{
return new inout Test!(Unqual!(typeof(member)))(member);
}
inout(I) opIndex(size_t idx) inout
{
static if (is(T == struct))
{
switch (idx)
static foreach (index, t; T.tupleof)
{
case index:
return new inout
Test!(Unqual!(typeof(this.member.tupleof[index])))
(this.member.tupleof[index]);
default:
return null;
}
}
else
return null;
}
}
auto test(T)(inout T t)
{
return new inout Test!(Unqual!T)(t);
}
class TestA(T : T[])
{
Test!T[] arr;
// ERROR: Can't initialize inout variable in a for loop...
this(inout(T[]) arr) inout
{
// 1: Nope
foreach (mem; arr)
this.arr ~= test(mem);
// 2: Nope
//Test!T[] a;
//foreach (mem; arr)
// a ~= test(mem);
On the right track, but inside inout (or const or immutable)
constructors, the members can only be initialized once. So you have to
initialize a local, and then set the member once.
The issue is, your input is *also* inout (a necessary condition), so you
didn't declare a properly:
inout(Test!T)[] a;
foreach (mem; arr) a ~= test(mem);
this.arr = a;
-Steve
