Operator overloading, structs

[Yigal Chripun]

bearophile wrote:

> 

> So with your current changes to BigInt, in the following program to
replace the int "i" with a BigInt:
> 
> void main() {
>     int i = 1;
>     if (i)
>         i++;
>     auto a = [10, 20, 30, 40];
>     printf("%d\n", a[i]);
> }
> 
> you need to change the code like this:
> 
> void main() {
>     BigInt i = 1;
>     if (i != 0)
>         i++;
>     auto a = [10, 20, 30, 40];
>     printf("%d\n", to!(long)a[i]);
> }
> 
> The toBool will help avoid the change in the second line.
> 
> I'd like to change programs as little as possible when I change the
> type of a variable from int to BigInt. This has also the big
> advantage that I can write templated algorithms that work with both
> ints and BigInts with as few "static if" as possible (to manage
> BigInts in a special way, for example adding that to!(long) ). That's
> why in such situation an implicit casting is handy.
> 

why not just use (i != 0) in both cases? this should work with any 
numeric type (so it'll be used in generic code).

conversion of ints to bools in C is IMO a hole in the type system due to 
the lack of a boolean type in C. All those narrowing implicit casts 
inherited from C are a bad idea IMO.

the need to convert the bigInt to long in order to print it is a design 
error in printf() - the format string should specify the formatting of 
the variables not their types.