accessing numeric template parameters

[Philippe Sigaud via Digitalmars-d-learn]

On Mon, Nov 3, 2014 at 3:27 PM, Dominikus Dittes Scherkl via
Digitalmars-d-learn <digitalmars-d-learn at puremagic.com> wrote:
> If I have a struct with numeric template parameter, how can I access it
> within member functions? Like normal member variables? And how about the
> constructor?
>
> struct polynomial(uint base)
> {
> private:
>    uint[] N;
> public:
>    this(uint x) { base = x; }

base is part of the type. polynomial is just a 'recipe' for a type,
the real struct would be Polynomial!(0), Polynomial!(1), etc. Note
that Polynomial!0, Polynomial!1, ... are all different types.

Being part of the type means it's defined only at compile-time, you
cannot use a runtime value (like 'x') to initialize it.

Note that with your current code, `base' is not visible outside
Polynomial. You can alias it to a field to make it visible:

struct Polynomial(uint base)
{
    alias b = base; // b is visible outside (but set at compile-time !)
...
}

You can create one like this:

Polynomial!2 poly;
poly.N = [0,1,0,0,1,1];

assert(poly.b == 2);

Of course, you cannot change b: `poly.b = 3;' is forbidden.