indexing a tuple containing a struct strange result
What is going on here?
import std.stdio, std.typecons;
struct S
{
int x;
Tuple!(S) foo() { return tuple(this); }
}
void main()
{
S s;
s.x = 8;
writeln((s.foo())); //output: Tuple!(S)(S(8))
writeln((s.foo())[0]); //output: S(0)
}
Re: indexing a tuple containing a struct strange result
On Monday, 24 June 2013 at 01:22:12 UTC, cal wrote:
What is going on here?
import std.stdio, std.typecons;
struct S
{
int x;
Tuple!(S) foo() { return tuple(this); }
}
void main()
{
S s;
s.x = 8;
writeln((s.foo())); //output: Tuple!(S)(S(8))
writeln((s.foo())[0]); //output: S(0)
}
import std.stdio, std.typecons;
struct S
{
int x;
int y;
int z;
auto foo() { return tuple(this.tupleof); }
}
void main()
{
S s;
s.x = 8;
s.y = 9;
s.z = 10;
writeln((s.foo())); //output: Tuple!(int, int, int)(8, 9,
10)
writeln(s.foo()[2]); //output: 10
}
Is this what you expected?
I would explain what's going on but I'd be wrong.
Re: indexing a tuple containing a struct strange result
On 06/23/2013 09:40 PM, Anthony Goins wrote:
> On Monday, 24 June 2013 at 01:22:12 UTC, cal wrote:
>> Tuple!(S) foo() { return tuple(this); }
> import std.stdio, std.typecons;
>
> struct S
> {
> int x;
> int y;
> int z;
>
> auto foo() { return tuple(this.tupleof); }
> }
>
> void main()
> {
> S s;
> s.x = 8;
> s.y = 9;
> s.z = 10;
> writeln((s.foo())); //output: Tuple!(int, int, int)(8, 9, 10)
>
> writeln(s.foo()[2]); //output: 10
> }
>
> Is this what you expected?
I think the OP is asking about the difference from when foo() is a
non-member function:
import std.stdio, std.typecons;
struct S
{
int x;
}
Tuple!(S) foo(S s)
{
return tuple(s);
}
void main()
{
S s;
s.x = 8;
writeln((s.foo())); //output: Tuple!(S)(S(8))
writeln((s.foo())[0]); //output: S(8)
}
This time the output is S(8).
I think it is a compiler bug.
Ali
Re: indexing a tuple containing a struct strange result
On 06/23/2013 10:07 PM, Ali Çehreli wrote:
> I think it is a compiler bug.
Make that a Phobos bug. :)
The following is a reduced program that exhibits the problem. The
presence or absence of the unused member function makes a difference:
import std.typecons;
struct S
{
int x;
// Bizarre: Comment-out this function to pass the assert in main.
Tuple!(S) unused()
{
return tuple(S(7));
}
}
void main()
{
auto s = S(8);
assert(tuple(s).expand[0] == S(8));
}
Ali
Re: indexing a tuple containing a struct strange result
On Monday, 24 June 2013 at 05:31:29 UTC, Ali Çehreli wrote:
On 06/23/2013 10:07 PM, Ali Çehreli wrote:
> I think it is a compiler bug.
Make that a Phobos bug. :)
The following is a reduced program that exhibits the problem.
The presence or absence of the unused member function makes a
difference:
import std.typecons;
struct S
{
int x;
// Bizarre: Comment-out this function to pass the assert in
main.
Tuple!(S) unused()
{
return tuple(S(7));
}
}
void main()
{
auto s = S(8);
assert(tuple(s).expand[0] == S(8));
}
Ali
Actually I hadn't tried with free functions, but this test
captures my problem. I'll file it now. Thanks!
Re: indexing a tuple containing a struct strange result
On 06/23/2013 11:11 PM, cal wrote: I'll file it now. Thanks! Thanks for filing: http://d.puremagic.com/issues/show_bug.cgi?id=10458 Ali
