[Seed7-users] Seed7 - Using References

[Zaakari <Za...@pr...>]

Ah, it never registered with me before that I had to use interfaces to pass references around.

So then, given:

const type: Point is new interface;
const type: Flashy is new struct
type_implements_interface(Flashy, Point);

Not only is your example possible (same-level reassignment):

var Point: a is Flashy.value;
var Flashy: b is Flashy.value;
var Flashy: c is Flashy.value;

a := b;
# make adjustments to b using a...
a := c;
# make adjustments to c using a...

But also reassignment via function (given that a, b and c were all declared outside the function):

(* A simple example here, but--in reality--the second parameter would end up being either an array or a containing object *)
const proc: switch_to (inout Point: base, in Point: target) is func
begin
base := target; # target isn't local, so all is well.end func;

switch_to(a, b);
# make adjustments to b using a...
switch_to(a, c);
# make adjustments to c using a...

In the past, I was doing something similar to this without templates, and it was a huge pain (basically using integers to remember object offsets within arrays); so thank you for clearing up the confusion for me (my desire to use Seed7 has been renewed ;).

Zachary