Why are opEquals/opCmp arguments not in or const for Objects?

[Stewart Gordon]

On 21/03/2013 07:51, Jonathan M Davis wrote:
> On Thursday, March 21, 2013 08:29:28 deadalnix wrote:
>> Wouldn't that trigger bunch of false warning on legitimate
>> overloaded opSomething ?
>
> I'm not sure that overriding a deprecated function triggers a deprecation
> warning, but regardless, for opEquals and opCmp, that wouldn't be a problem,
> because all classes would be being changed so that their opEquals and opCmp
> don't take Object, so the deprecation warnings would be a _good_ thing.

The problem really is that the D runtime references these methods of 
Object.  So the process would be something like this:
(a) reimplement AAs using templates
(b) rewrite any other code that depends on these methods of Object 
(sorting out TypeInfo might be tricky)
(c) and then deprecate these methods

Code that defines opEquals(Object) or opCmp(Object), either instead of 
or as a call to a class-specific version, will still work during this 
phase-out.  But I'm inclined to agree that trying to override a 
deprecated method without declaring the override as deprecated should 
trigger a deprecation error.

> It would probably be more of a problem for toString and toHash
> though, since they don't take arguments. Deprecating them won't work
> if overriding them triggers deprecation warnings, and the fact that
> you'll be forced to override them as long as they're in Object and
> then won't be allowed to once they're out of Object will probably
> mean simply removing them from one release to another and forcing
> everyone to immediately change their toHash and toString methods so
> that they don't break.
<snip>

Yes, it does seem that we would need something to accommodate this. 
Maybe a way to mark a deprecated method so that it can be overridden 
without the override attribute, but overriding it with the override 
attribute will trigger a deprecation error.  But would this feature get 
any real use after we've got rid of these methods from Object?

Stewart.