Re: Pre-RFC proposal: opt-in implicit interfaces / structural typing

On 7 November 2025 21:34:56 GMT, Larry Garfield <larry@garfieldtech.com> wrote: >__toString() is *old*. It may go all the way back to 5.0, but it was there at least as of 5.2. >The problem is that there was no way to type against it. I know all that. I've just never understood why you would *want* to type against it. The only thing you can do with that knowledge is turn the object into a string, so why not just ask for a string in the first place? But I apologise for drifting off topic; the relevant point is that it works exactly how the proposed implicit interfaces would, so whatever reasoning was used for it might serve a useful example for other potential uses. If nothing else, being able to say "it's a built-in implicit interface" would be less confusing than explaining it as a magical special case. Who knows, maybe there are people wishing they could type against other magic methods, who could do so by declaring their own implicit interfaces. As I say, I'm personally much more interested in highly explicit code, so am more likely to go completely the opposite direction: use an *empty interface*, where the only thing you're doing is "tagging" a class as intended for a particular purpose. But, I know there are people who like "duck typing", and implicit interfaces or structural typing give a way to formalise that, so I can see value for those people. Rowan Tommins [IMSoP]