Hi, I'm unfortunately in D this construction is not possible to define:

class A(T){
    abstract void method(S)(T arg1,S arg2);
}

As adding S to function declaration makes it not virtual.

But we can add this kind of functionality using mixin templates

mixin template BaseMix(T,S){
   abstract void method(T arg1,S arg2);
}

class Base{
   mixin BaseMix!(int,int);
}

//we can create now implementation by creation of other mixin
mixin template ImplMix(T,S){
   override void method(T arg1,S arg2){
    import std.stdio;
    writeln(T.strinof," ",S.stringof);
    //some dummy implementation
   }
}
//and initiate the class

class Impl:Base{
   mixin ImplMix!(int,int);
}

OK but i don't want to write each argument to mixin templates invocations
like:
   mixin ImplMix!(int,int);
   mixin ImplMix!(int,byte);
   mixin ImplMix!(int,string);
   mixin ImplMix!(int,Object);
   mixin ImplMix!(int,ubyte); etc.
It may produce a bug susceptible code as i would have to write it in two class definitions.

I created template that automatically calls mixins with PList... passed but i can't call it with mixins having more than one template param like ImplMix(T,S)


template MixinTypeIterate(alias mixinTemplate,TList...){
	static if(TList.length>0){
		mixin mixinTemplate!(TList[0]);
		static if(TList.length>1){
			mixin MixinTypeIterate!(mixinTemplate,TList[1..$]);
		}
	}
	
	
}
how to alias mixin template to be able to pass it to this one ?

class BaseClass(T){
   protected alias Types=AliasSeq!(int,string,ubyte);
   private alias WrappedMix(S)=mixin Mix!(T,S); //not compiles - mixins are no t regular templates
   mixin MixinTypeIterate!(WrappedImplMix,Types);
}
class ImplClass(T){
   private alias WrappedMix(T)=mixin ImplMix!(T,S); //not compiles - mixins are no t regular templates
   mixin MixinTypeIterate!(WrappedImplMix,Types);
}

How to make it work?

	

On 08.04.2016 14:04, Voitech wrote:
> template MixinTypeIterate(alias mixinTemplate,TList...){
[...]
> }
> how to alias mixin template to be able to pass it to this one ?
>
> class BaseClass(T){
>     protected alias Types=AliasSeq!(int,string,ubyte);
>     private alias WrappedMix(S)=mixin Mix!(T,S); //not compiles - mixins
> are no t regular templates

private mixin template WrappedMix(S) {mixin BaseMix!(T, S);}

Fixed a typo here: Mix -> BaseMix.

>     mixin MixinTypeIterate!(WrappedImplMix,Types);
> }
> class ImplClass(T){
>     private alias WrappedMix(T)=mixin ImplMix!(T,S); //not compiles -
> mixins are no t regular templates

Ditto:

private mixin template WrappedMix(S) {mixin ImplMix!(T, S);}

Fixed another typo here: parameter T -> parameter S.

By the way, I find this very condensed style with no spaces around equals signs, after commas, or before braces quite hard to read.

>     mixin MixinTypeIterate!(WrappedImplMix,Types);
> }

Here's another thing that may be interesting to you. You can a have sequence of sequences by wrapping them in a non-eponymous template:

----
template Box(stuff ...) {alias contents = stuff;}

mixin template MixinTypeIterate(alias mixinTemplate, boxes ...)
{
    static if (boxes.length > 0)
    {
        mixin mixinTemplate!(boxes[0].contents);
        mixin MixinTypeIterate!(mixinTemplate, boxes[1..$]);
    }
}

mixin template simpleExample(T ...)
{
    void f(T args) {import std.stdio; writeln(args);}
}

mixin MixinTypeIterate!(simpleExample, Box!int, Box!(float, string));

void main()
{
    f(42);
    f(42.2, "foo");
}
----