how to do this meta-programming? print the address of random element's address of a variable length of arrays?

[mw]

On Saturday, 12 September 2020 at 03:11:09 UTC, Ali Çehreli wrote:
> On 9/11/20 6:44 PM, mw wrote:> e.g.
> >
> > int[] a = new int[la];
> > int[] b = new int[lb];
> > int[] c = new int[lc];
> > int[] d = new int[ld];
> >
> >
> > the func I want to write, e.g. for 2 arrays (instantiation)
> is like this:
> >
> > void print_random_elem_addr(int[] x, int[] y) {
> >    auto i = random_int_between(0, x.length);
> >    auto j = random_int_between(0, y.length);
> >    print(&(x[i], &(y[j]));  // only single print() func call
> allowed!
> > }
> >
> >
> > But I want one generic function, which can be called as:
> >
> > print_random_elem_addr(a, b);
> > print_random_elem_addr(a, b, c);
> > print_random_elem_addr(a, b, c, d);

Thanks for the reply.

> If they are all of same type like int[] in this case, then you

but, this is not the intention, we should suppose the array's are 
heterogeneous type ...

> can variable number of parameters, which means "any number of 
> int[] arrays" below, elements of which can be called either as 
> separate arguments or as a single array argument:
>
> import std.stdio;
> import std.random;
>
> void print_random_elem_addr(int[][] arrays...) {

... to prevent passing in parameters as array of array like this.

>   foreach (i, array; arrays) {
>     const chosen = uniform(0, array.length);
>     writefln!"Array %s, element %s: %s"(i, chosen, 
> &array[chosen]);

actually this writefln will be called n times.

I intentionally require:

   print(&(x[i], &(y[j]));  // only single print() func call 
allowed!


I.e. I want to learn the generic meta-programming way to assemble 
such parameter list (&(x[i], &(y[j])) at compile time, it is 
possible?