Making `object.opEquals' replaceable

[Kapps via Digitalmars-d]

On Thursday, 7 May 2015 at 14:37:14 UTC, Manfred Nowak wrote:
> According to the specs
>   http://dlang.org/operatoroverloading.html#equals
> `object.opEquals' denies to call the `opEquals'-function 
> tailored for the class of two objects `a' an `b' if for those 
> objects `a is b' holds.
>
> Although this seems resonable and reduces boiler-plate it makes 
> it impossible to implement a side-effect for those cases.
>
> I do not believe, that there is good reason to disallow 
> side-effects in those cases. Therefore a mechanism to enable 
> such side-effects should be implemented.
>
> -manfred

Having the base Object method check for 'is' itself results in 
not having to make a virtual call in, I would guess, about 40-50% 
of cases or even more. It's a performance benefit.