why are opCmp and opEquals not pure.

[Timon Gehr via Digitalmars-d]

On 09/17/2015 08:37 PM, Stefan Koch wrote:
> Hi,
> is there any reason why opCmp and opEquals are not pure ?

Not all reasonable implementation are. Arguably, the methods shouldn't 
even be on Object.

> I would argue it is very counter-intuitive to mutate any state when
> comparing objects.
> ...

Not if it is done to improve performance, but not visible semantics.

> opCmp and opEquals not being annotated pure is a major problem for me in
> writing ctfe-able code.
>
> since any call to Object.opEquals need to be warped in another function
> to be able to cast the Function pure.
>

I don't get this point. You don't need any annotations to write 
ctfe-able code. Also, I think there were some efforts to make a template 
out of core.object.opEquals, in order to preserve the attributes. (Such 
that, as long as one doesn't work with plain Objects, the missing pure 
annotation would have no influence.)