struct S { int a, b; }
auto s = cast(S)10;
//compiles and sets s.a to 10.

It works also for any other type, if the structure contains a member of that type in the first position.

Is this normal behaviour?

On 7/15/15 11:45 AM, rumbu wrote:
> struct S { int a, b; }
> auto s = cast(S)10;
> //compiles and sets s.a to 10.
>
> It works also for any other type, if the structure contains a member of
> that type in the first position.
>
> Is this normal behaviour?

I would say this is a bug. As far as I know, it's not defined in the spec.

-Steve

On Wed, 15 Jul 2015 15:45:43 +0000
"rumbu" <rumbu@rumbu.ro> wrote:

> struct S { int a, b; }
> auto s = cast(S)10;
> //compiles and sets s.a to 10.
> 
> It works also for any other type, if the structure contains a member of that type in the first position.
> 
> Is this normal behaviour?

Yes, this is OK

If you need to cast against diferent types you can try pointers:

import std.stdio;
struct S
{
	ubyte a;
	ubyte b;
}

void main() {
	ushort m = 65535;
	auto s = *(cast(S*)&m);
	writeln(s);
}

On Wed, 15 Jul 2015 11:57:01 -0400
Steven Schveighoffer <schveiguy@yahoo.com> wrote:

> On 7/15/15 11:45 AM, rumbu wrote:
> > struct S { int a, b; }
> > auto s = cast(S)10;
> > //compiles and sets s.a to 10.
> >
> > It works also for any other type, if the structure contains a member of that type in the first position.
> >
> > Is this normal behaviour?
> 
> I would say this is a bug. As far as I know, it's not defined in the spec.
> 
> -Steve
It is defined:

Casting a value v to a struct S, when value is not a struct of the same type, is equivalent to:

S(v)

On Wednesday, 15 July 2015 at 15:58:17 UTC, Daniel Kozák wrote:
>
> On Wed, 15 Jul 2015 15:45:43 +0000
> "rumbu" <rumbu@rumbu.ro> wrote:
>
>> struct S { int a, b; }
>> auto s = cast(S)10;
>> //compiles and sets s.a to 10.
>> 
>> It works also for any other type, if the structure contains a member of that type in the first position.
>> 
>> Is this normal behaviour?
>
> Yes, this is OK
>
> If you need to cast against diferent types you can try pointers:
>

In fact I'm trying to overload the cast operator in this case, I was surprised about the default casting since I didn't find any reference to this behaviour, nor in TDPL, nor online.

Since UFCS is not allowed in operator overloading I wonder if this is possible.