Menu
Search

Forums

Forum Index

Thread overview
nested templates using Complex! with slices, ... confused, I am!
Aug 09, 2021
james.p.leblanc
Aug 09, 2021
H. S. Teoh
Aug 09, 2021
Paul Backus
Aug 09, 2021
james.p.leblanc
August 09, 2021
Gravatar of james.p.leblancPosted by james.p.leblancReply
james.p.leblanc
Gravatar of james.p.leblanc


Reply

Suppose "foo_double" should return a complex double slice, with double input args.
Similarly "foo_float" should return a float slice, with float input args.

I thought it should be easy to parameterize with a template taking a SINGLE
argument, either a"double" or "float" as follows:

>

import std.stdio;
import std.complex;

Complex!double[] foo_double(double x, double y){
auto r = [x, x];
auto i = [y, y];
auto z = [ Complex!double(x, y), Complex!double(x,y) ];
return z;
}

Complex!float[] foo_float(float x, float y){
auto r = [x, x];
auto i = [y, y];
auto z = [ Complex!float(x, y), Complex!float(x,y) ];
return z;
}

T[] foo_temp(Complex!T[])(T x, T y){
auto r = [x, x];
auto i = [y, y];
auto z = [ Complex!T(x, y), Complex!T(x,y) ];
return z;
}

void main(){
auto yd = foo_double(1.1, 2.2);
writeln(yd); ...
}

But, no ... I am WRONG! I get the message:

qqq.d(18): Error: identifier expected for template value parameter

Nested templates using Complex! really have me confused. How should I
be thinking about such things in order to understand better?

Best Regards,
James

August 09, 2021
Gravatar of H. S. TeohPosted by H. S. Teoh
in reply to james.p.leblanc		Reply
H. S. Teoh
Gravatar of H. S. Teoh
Posted in reply to james.p.leblanc


Reply
On Mon, Aug 09, 2021 at 06:35:56PM +0000, james.p.leblanc via Digitalmars-d-learn wrote: [...]
> > **T[] foo_temp(Complex!T[])(T x, T y){
> >   auto r = [x, x];
> >   auto i = [y, y];
> >   auto z = [ Complex!T(x, y), Complex!T(x,y) ];
> >   return z;
> > }**

Your syntax is wrong; the declaration should be:

	Complex!T[] foo_temp(T)(T x, T y) { ... }

Basically, you're parametrizing on T, and returning an array of a Complex type built upon T.


T

-- 
Curiosity kills the cat. Moral: don't be the cat.
August 09, 2021
Gravatar of Paul BackusPosted by Paul Backus
in reply to james.p.leblanc		Reply
Paul Backus
Gravatar of Paul Backus
Posted in reply to james.p.leblanc


Reply

On Monday, 9 August 2021 at 18:35:56 UTC, james.p.leblanc wrote:

> > 
T[] foo_temp(Complex!T[])(T x, T y){
  auto r = [x, x];
  auto i = [y, y];
  auto z = [ Complex!T(x, y), Complex!T(x,y) ];
  return z;
}

void main(){
auto yd = foo_double(1.1, 2.2);
writeln(yd); ...
}

But, no ... I am WRONG! I get the message:

qqq.d(18): Error: identifier expected for template value parameter

I think what you want is:

Complex!T[] foo_temp(T)(T x, T y) {
  auto r = [x, x];
  auto i = [y, y];
  auto z = [ Complex!T(x, y), Complex!T(x,y) ];
  return z;
}

This is what I get when I take one of the non-template versions and replace float or double with T.

August 09, 2021
Gravatar of james.p.leblancPosted by james.p.leblanc
in reply to Paul Backus		Reply
james.p.leblanc
Gravatar of james.p.leblanc
Posted in reply to Paul Backus


Reply

On Monday, 9 August 2021 at 18:44:34 UTC, Paul Backus wrote:

>

On Monday, 9 August 2021 at 18:35:56 UTC, james.p.leblanc wrote:

> > 
T[] foo_temp(Complex!T[])(T x, T y){
  auto r = [x, x];
  auto i = [y, y];
  auto z = [ Complex!T(x, y), Complex!T(x,y) ];
  return z;
}

void main(){
auto yd = foo_double(1.1, 2.2);
writeln(yd); ...
}

But, no ... I am WRONG! I get the message:

qqq.d(18): Error: identifier expected for template value parameter

I think what you want is:

Complex!T[] foo_temp(T)(T x, T y) {
  auto r = [x, x];
  auto i = [y, y];
  auto z = [ Complex!T(x, y), Complex!T(x,y) ];
  return z;
}

This is what I get when I take one of the non-template versions and replace float or double with T.

H.S & Paul,

Wow, thanks for the quick replies!

It all seems so simple now ... but I just could not see it!

I had been completely (and confidently, unfortunately) misunderstanding
the syntax of that left most column.

Thanks again,
James