[PPC0030] - Clarifications on `use overload` interaction

[leonerd]

The PPC document doesn't actually talk about use overload at all.

In the course of implementing it (Perl/perl5#24304), currently I have fully created an overload category for the equ and === operators, allowing a class to use overload equ => ... to specify its overloading behaviour here.

But I wonder if this should be considered correct, or not. We say that the equ operator's behaviour can be explained in terms of some defined checks and the eq operator. While we allow the eq operator to be overloaded, we don't allow defined to be.

I wonder if therefore, we should say that equ (and related) are not independently overloadable, but instead are just implemented in exactly these terms - a defined check first that cannot be overridden, followed by a possibly-overloaded eq check.

[Grinnz]

In my opinion since I don't see a particular reason that such an overload would be useful, we should take the simpler approach of not providing an independent overload. Such a feature can be added at such time as it's desired.

[leonerd]

Such a feature can be added at such time as it's desired.

Yeah I guess that's the safest way to do it. Don't add it for now but consider maybe adding later, if needed. But not adding it now doesn't get in the way of that.