Issue 3789, stucts equality

[Artur Skawina]

On 03/29/12 14:07, Andrej Mitrovic wrote:
>  3/29/12, Andrej Mitrovic <andrej.mitrovich at gmail.com> wrote:
>> snip
> 
> Crap, lockstep doesn't work on different types, it was iterating over
> the arrays. That went over my head. A slightly complicated version
> that actually works:
> 
> import std.stdio;
> import std.conv;
> 
> string tupleCompare(int len)()
> {
>     string result;
>     foreach (i; 0 .. len)
>     {
>         result ~= "
>             if (this.tupleof[" ~ to!string(i) ~ "] != t.tupleof[" ~
> to!string(i) ~ "])
>                 return false;
>         ";
>     }
>     return result;
> }
> 
> template safeOpEquals()
> {
>     bool opEquals(typeof(this) t)
>     {
>         enum len = typeof(this).tupleof.length;
>         mixin(tupleCompare!len);
>         return true;
>     }
> }

// D does make things easy:
template safeOpEquals()
{
   bool opEquals(T)(T t) {
      foreach (i, v; this.tupleof )
         if (v != t.tupleof[i])
            return 0;
      return 1;
   }
}

struct Foo
{
    int[] arr;
    string s;
    mixin safeOpEquals;
}


You may also want to include something like

>   static if (!is(typeof(this)==T))
>      return 0;
>   else
>      foreach etc...

to make it return false, instead of failing at compiletime when
comparing different types.

artur