• Manfred Nowak (12/12) May 04 2015 class C{
• anonymous (3/15) May 04 2015 because `c is c`
• Manfred Nowak (9/10) May 05 2015 Thanks. One can see this documented in
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (12/21) May 05 2015 There is now way in D other than changing the implementation:

"Manfred Nowak" <svv1999 hotmail.com> writes:

class C{
   override bool opEquals( Object o){
     return true;
   }
}
unittest{
   auto c= new C;
   assert( c == c);
}

`rdmd --main -unittest -cov' shows, that opEquals is not 
executed. Why?

-manfred

"anonymous" <anonymous example.com> writes:

On Tuesday, 5 May 2015 at 04:09:03 UTC, Manfred Nowak wrote:
 class C{
   override bool opEquals( Object o){
     return true;
   }
 }
 unittest{
   auto c= new C;
   assert( c == c);
 }

 `rdmd --main -unittest -cov' shows, that opEquals is not 
 executed. Why?

 -manfred

because `c is c`

https://github.com/D-Programming-Language/druntime/blob/0ac255d7276b9b825eb6f1e677e9ee4f5ad49ca2/src/object.di#L61

"Manfred Nowak" <svv1999 hotmail.com> writes:

On Tuesday, 5 May 2015 at 05:26:17 UTC, anonymous wrote:

 because `c is c`

Thanks. One can see this documented in
   http://dlang.org/operatoroverloading.html#equals

But
1: how can one override this behavior
2: what is the design reason for this

Especially: how can one implement side effects on invoking `==' 
or `!='?

-manfred

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 05/05/2015 04:30 PM, Manfred Nowak wrote:
 On Tuesday, 5 May 2015 at 05:26:17 UTC, anonymous wrote:

 because `c is c`

 Thanks. One can see this documented in
    http://dlang.org/operatoroverloading.html#equals

 But
 1: how can one override this behavior

There is now way in D other than changing the implementation:

 
https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L141

(There is also object.di there but I think changing the function above 
should be sufficient.)

 2: what is the design reason for this

I am guessing:

- For correctness, an object should be equal to itself

- Preventing memory errors when the left-hand side object is null.

- Reducing boilerplate

 Especially: how can one implement side effects on invoking `==' or `!='?

 -manfred

Can you use a member function instead as in c.eq(c)?

Ali