Generic Span/Limits/MinMax Type

[sclytrack]

On Monday, 20 January 2014 at 19:36:13 UTC, Nordlöw wrote:
> Has anyone cooked up a generic D struct that groups together min
> and max values of a type and default-initializes them in the
> correct way?
>
> Something like
>
>      struct Limits(T)
>      {
>          /* TODO: Fix purity of this by fixing Bytes.value() */
>          auto init() @trusted /* pure */ nothrow { return
> tuple(T.max,
>
> T.min); }
>          alias _minmax this;
>          Tuple!(T,T) _minmax;
>      }
>      auto limits(T)() { return Limits!T(); }
>      unittest {
>          Limits!int x;
>          dln(x);
>      }
>
> I want min and max to default initialize to T.max, T.min so they
> are prepared for x = min/max(x, ...) arithmetic. But the code
> above doesn't work because the init() function isn't called and 
> I
> don't know why. And I can't use default member initialization
> because I want `Limits` to work also with types such as 
> `SysTime`
> when min and max are only know at run-time.
>
> I'm aware of `std.datetime.span` but it isn't generic.
>
> Ideas anyone?

import std.stdio;
import std.typecons;

struct Limits(T)
{
	auto _minmax = tuple(T.min, T.max);
	alias _minmax this;
}


void main()
{

	auto a = tuple(int.min, int.max);
  	a[1] = 2;
	writeln(a);

	Limits!int x;
	writeln(x._minmax);
	writeln(x);
	x[0] = 1;
	writeln(x);
	writeln("end");
}


I'm not sure what you want to do.