Template shenannigans with multiple datatypes

[Chris Katko]

On Friday, 13 May 2022 at 07:05:36 UTC, vit wrote:
> On Friday, 13 May 2022 at 06:43:39 UTC, Chris Katko wrote:
>> I have an intrinsicGraph(T) class that is given a pointer to a 
>> T dataSource and automatically polls that variable every frame 
>> to add it to the graph, whether it's a float, double, integer, 
>> and maybe bool.
>>
>> [...]
>
> I dont understand first qestion but second question has a 
> solution:
>
> ```d
> intrinsic_graph!T make_graph(T, Args...)(auto ref T val, auto 
> ref Args args){
> 	return new intrinsic_graph!T(val, args);
> }
>
>
> instrinsicGraph!float testGraph;
> instrinsicGraph!ulong testGraph2;
> // later
> testGraph = make_graph(units[0].x, 100, 300, COLOR(1,0,0,1));
> testGraph2 = make_graph(g.stats.fps, 100, 500, COLOR(1,0,0,1));
>
>
> ```

Okay, to clarify just in case I'm very confusing because I'm up 
late.

If I wanted a "multipleGraph". A graph that takes multiple values 
and plots them on the same graph. I need to store a buffer for 
each dataSource. Luckily, because I'm painting them to the 
screen, the buffers only really need to be float even if they 
started as a boolean, int, or double. However, if I'm keeping a 
list of pointers to things I want to snoop when I call onTick(), 
I can't think of a way to support multiple types:

```D
class intrinsicGraph(T)
    {
    T* dataSource;
    float[] buffer;

    void onTick()
      {
      //grab datasource data and do something.
      buffer ~= to!float(*datasource);
      }
    }

auto g = intrinsicGraph!float(&myFloat);
```

But what if there's multiple types?

```D
class multiGraph(???)
    {
    ???[] dataSources;
    float[] buffers;

    void onTick()
      {
      //grab datasource data and do something.
      foreach(d, i; dataSources)
         buffers[i] ~= to!float(*d); //or whatever
      }
    }

auto g = multiGraph!???(&myFloat, &myDouble, &myInteger);

```

This is a kinda "dynamic language" feature but it feels like this 
information is theoretically, knowable at static, compile-time. I 
know what the variable types will be at compile-time, but I don't 
know how to put them all in one class and reference them 
automatically.