sorting a mutable array of immutable objects

[Anonymouse via Digitalmars-d]

On Wednesday, 20 April 2016 at 10:32:42 UTC, Jeff Thompson wrote:
> On Wednesday, 20 April 2016 at 09:54:13 UTC, Jeff Thompson 
> wrote:
>> I can create a mutable array of immutable objects, thanks to 
>> the answers to my other question 
>> https://forum.dlang.org/post/nf57f5$e6v$1@digitalmars.com .
>>
>> Now I want to sort the array.
>
> I found a solution, but I'm not sure it is the best way. 
> Instead of overriding opCmp, class C just defines a static 
> comparison to use with sort (which automatically works with 
> Rebindable). Is there a way to do this where I don't need to 
> specify C.isLess every time I sort?
>
> class C {
>   this(int x) immutable { this.x = x; }
>   static bool isLess(const C a, const C b) @safe pure nothrow { 
> return a.x < b.x; }
>   int x;
> }
>
> void
> main(string[] args)
> {
>   auto array = new Rebindable!(immutable(C))[2];
>   array[0] = new immutable C(20);
>   array[1] = new immutable C(10);
>   sort!(C.isLess)(array);
> }

int opCmp(immutable Object o) immutable {}

That seems to work for me. You want to make it const Object and 
inout if you want it to work on const and mutable C's as well. 
Also note that sort (std.algorithm.sorting : sort) returns a 
range and doesn't sort in place.

(Lastly this is probably more at home in the Learn forum.)