• Sclytrack (14/14) Mar 11 2008 With struct inheritance I mean the following and not the "concept interf...
• Frank Benoit (3/4) Mar 11 2008 See also this thread
• Sclytrack (13/13) Mar 11 2008 Forget what I said, I see that there is already something specified in t...
• Koroskin Denis (32/47) Mar 11 2008 As of now, it's not implemented.
• Christopher Wright (8/9) Mar 11 2008 If you're going to have any syntax for it, why not use the same syntax

Sclytrack <sclytrack pi.be> writes:

With struct inheritance I mean the following and not the "concept interfaces".

struct Base
{
  void doStuff()
  {
  }
}

struct Derived
{
  inherit Base base;
}


  Derived d;
  d.doStuff();


Sort of like having a compile time inheritance, with its limitations.

Frank Benoit <keinfarbton googlemail.com> writes:

Sclytrack schrieb:
 Sort of like having a compile time inheritance, with its limitations.

See also this thread
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=64764

Sclytrack <Sclytrack pi.be> writes:

Forget what I said, I see that there is already something specified in the
"WalterAndrei.pdf". Something called "alias this" and I forgot about it.

"allows importing the fields of a member into the namespacece of a struct."

	struct M {int a; }
	struct S {
		M m;
		alias m this;
		int b;
	}

	S s;
	b.a;
	s.b;

Wonder if it works with member functions too.

"Koroskin Denis" <2korden gmail.com> writes:

On Tue, 11 Mar 2008 14:02:26 +0300, Sclytrack <Sclytrack pi.be> wrote:

 Forget what I said, I see that there is already something specified in  
 the
 "WalterAndrei.pdf". Something called "alias this" and I forgot about it.

 "allows importing the fields of a member into the namespacece of a  
 struct."

 	struct M {int a; }
 	struct S {
 		M m;
 		alias m this;
 		int b;
 	}

 	S s;
 	b.a;
 	s.b;

 Wonder if it works with member functions too.

As of now, it's not implemented.

Your best best whould be to use mixins, and it's almost 100% same syntax:

template Base()
{
     void doStuff()
     {
     }
}

struct Derived
{
     mixin Base;
}

as opposed to:

struct Base
{
   void doStuff()
   {
   }
}

struct Derived
{
   inherit Base base;
}

However, you still can't cast Derived to Base. And proposed syntax (one  
with aliased this) most probably won't too (at least, S doesn't look like  
it inherits M).

I still think that structs should just support inheritance, maintaining  
the limitation of not having virtual functions. Classes could also benefit  
 from deriving from structs, although this most probably won't ever happen,  
since classes are reference types and most importantly contain _vtptr as a  
first member and therefore no casting is possible between them.

Christopher Wright <dhasenan gmail.com> writes:

Sclytrack wrote:
 With struct inheritance I mean the following and not the "concept interfaces".

If you're going to have any syntax for it, why not use the same syntax 
that you get with classes?

You'd have no polymorphism; the only benefits would be transparent 
aggregation and maybe `is (DerivedStruct : BaseStruct)` would return true.

However, you can get automatic aggregation with some (perhaps slightly 
tedious) template magic. I'm not interested in writing it, though, 
because it's tedious and fulfills no need for me.