Re: The future of objects and operators

On Fri, May 13, 2022, at 9:05 AM, Rowan Tommins wrote: > On 6 May 2022 23:16:37 BST, Jordan LeDoux <jordan.ledoux@gmail.com> wrote: >>I'm not sure at this point how voters think objects and operators should >>work together into the future. I'd like to see if anyone is willing to have >>high-level discussion about the ideas, instead of picking at the >>implementation or details of a particular RFC. > > > Hi Jordan, > > I like Larry's "4 levels", but I've been thinking that there's some > existing functionality in PHP which takes a different direction: rather > than overloading *operators*, the language lets you overload > *behaviour*. We have magic methods like __get and __call, and > interfaces like Iterator, Countable, and ArrayAccess. Some hook into a > particular function, or even operator, but they're generally described > in terms of what they do, not what they look like, if you see what I > mean. > > From that point of view, overloading comparison and equality > *behaviour* makes sense - it could affect not just the == and <=> > operators, but things like in_array() and sort(). I think this > distinction is more pronounced in PHP than some languages, because the > standard library isn't "self-hosted": a sort() call doesn't literally > compile to a call to $a <=> $b > > It's less obvious how that applies to mathematical operators - should > implementing "addition" allow an object to be used with array_sum() > perhaps? And what about deriving one operation from another, e.g. > $foo*3 running $foo+$foo+$foo, or $foo**3 running $foo*$foo*$foo? > > I don't really have a conclusion here, I just wanted to throw it out > there as a different mental model to consider. Interesting point. I think that's the most compelling argument I've heard for using public function __lessThan rather than operator <. I'm not sure if it's enough to change my own preference on that front, but it's an interesting point. Working with in_array() and sort() is a necessary feature for comparison overloading, IMO. I'm unsure about something like array_sum(), but could be convinced. Hum. --Larry Garfield