• Hakan Aras (14/14) Aug 08 2018 Given this:
• Alex (7/21) Aug 08 2018 I suppose, this is too slack.
• Hakan Aras (3/4) Aug 08 2018 Ah thanks, I was wondering if something like that exists. Still
• Jonathan M Davis (23/37) Aug 08 2018 Num n = 5;

Hakan Aras <hakan.aras live.at> writes:

Given this:

struct Num
{
     this(int a) {}
}

Is there any reason why this works:

Num n = 5;

but this doesnt:

Num funk()
{
     return 5;
}


I understand that I can construct it explicitely, but that gets 
annoying quickly, especially with templates.

Alex <sascha.orlov gmail.com> writes:

On Wednesday, 8 August 2018 at 08:15:16 UTC, Hakan Aras wrote:
 Given this:

 struct Num
 {
     this(int a) {}
 }

 Is there any reason why this works:

 Num n = 5;

 but this doesnt:

 Num funk()
 {
     return 5;
 }


 I understand that I can construct it explicitely, but that gets 
 annoying quickly, especially with templates.

I suppose, this is too slack.

What would work is

Num funk()
{
     return typeof(return)(5);
}

Hakan Aras <hakan.aras live.at> writes:

On Wednesday, 8 August 2018 at 08:44:03 UTC, Alex wrote:

     return typeof(return)(5);

Ah thanks, I was wondering if something like that exists. Still 
though, that's 16 extra characters that dont need to be there.

Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:

On Wednesday, August 8, 2018 2:15:16 AM MDT Hakan Aras via Digitalmars-d-
learn wrote:
 Given this:

 struct Num
 {
      this(int a) {}
 }

 Is there any reason why this works:

 Num n = 5;

 but this doesnt:

 Num funk()
 {
      return 5;
 }


 I understand that I can construct it explicitely, but that gets
 annoying quickly, especially with templates.

Num n = 5;

doesn't actually do an implict conversion. It's the same as doing

Num n = Num(5);

So, I guess that you could call it implicit construction, but regardless,
it's just a different syntax for calling the constructor. The only way to
create an implicit conversion with a user-defined type in D is to use alias
this, and that only provides a way to implicitly convert _from_ a
user-defined type, not to a type. So, having

Num funk()
{
    return 5;
}

work is impossible in D, just like having something like

auto foo(Num n)
{
    ...
}

foo(5);

work is impossible. If you want to return an int and have it converted to a
Num, then you're going to need to explicitly construct a Num from the int.

- Jonathan M Davis