• Agustin (15/15) Oct 19 2013 I'm trying to implement a template Vector and i would like to
• TheFlyingFiddle (31/46) Oct 19 2013 From your post i guess that the goal here is to do
• TheFlyingFiddle (1/2) Oct 19 2013 Should be res += components[i] * components[i];

"Agustin" <agustin.l.alvarez hotmail.com> writes:

I'm trying to implement a template Vector and i would like to 
know if this is possible.

My current vector class is:

public class Vector(T, size_t size) {
     private T components[size];
}

And i would like to implement a property as this:

 property
public size_t length() const {
     return Trait.ExpandFor(size, components, Function(+, (n, 
j))); // Kind of messy but you get my point.
}

instead of doing for(...) over a array i would like to make a 
trait that produce this code

return (x * x + y * y + z * z + ...)

"TheFlyingFiddle" <theflyingfiddle gmail.com> writes:

On Saturday, 19 October 2013 at 15:22:31 UTC, Agustin wrote:
 I'm trying to implement a template Vector and i would like to 
 know if this is possible.

 My current vector class is:

 public class Vector(T, size_t size) {
     private T components[size];
 }

 And i would like to implement a property as this:

  property
 public size_t length() const {
     return Trait.ExpandFor(size, components, Function(+, (n, 
 j))); // Kind of messy but you get my point.
 }

 instead of doing for(...) over a array i would like to make a 
 trait that produce this code

 return (x * x + y * y + z * z + ...)

 From your post i guess that the goal here is to do
loop unrolling.

A simple way to achive this is to force a loop unrool
by iterating over a TypeTuple.

module vector;
import std.typetuple;


class Vector(T, size_t size)	{
     private T[size] components;

     public T length() const  //Guessing this is vector magnitude
     {	
	T res = 0;
	foreach(i; staticIota!(0u, size)) //Unrools the loop at 
compile-time.
	{
   	    res += components[i];
	}

	return cast(T)std.math.sqrt(res);
     }
}

//Creates a range from start inclusive to end exclusive.
template staticIota(size_t start, size_t end)
{
     static if(start == end)
	alias TypeTuple!() staticIota;
     else static if(start < end)
	alias TypeTuple!(start, staticIota!(start + 1, end)) staticIota;
     else
	static assert(0, "start cannot be greater then end!");
}


This works since the value _size_ is avalible at compile-time.

"TheFlyingFiddle" <theflyingfiddle gmail.com> writes:

   	    res += components[i];

Should be res += components[i] * components[i];