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Date: Sat, 07 Aug 2021 09:28:54 -0500
To: "php internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Revisiting Userland Operator Overloads
From: larry@garfieldtech.com ("Larry Garfield")

On Fri, Aug 6, 2021, at 3:18 PM, Scott Arciszewski wrote:
> My recommendation is to have a base interface for every operator that can
> be overloaded, so that these can be composed together.
> 
> AddOverloadInterface { __overloadAdd(): self; }
> SubOverloadInterface { __overloadSub(): self; }
> MulOverloadInterface { __overloadMul(): self; }
> DivOverloadInterface { __overloadDiv(): self; }
> ModOverloadInterface { __overloadMod(): self; }
> LeftShiftOverloadInterface { __overloadLeftShift(): self; }
> RightShiftOverloadInterface { __overloadRightShift(): self; }
> XorOverloadInterface { __overloadXor(): self; }
> etc.
> 
> Then if you were implementing matrix math, you could do this:
> 
> MatrixMath implements AddOverloadInterface, SubOverloadInterface,
> MulOverloadInterface {
> 
> }

That would be roughly how Stringable/__toString works now.  I'd be OK with that, if it's going to be a language trend.

> This prevents you from having to define methods for operations you don't
> support.
> 
> It's probably worth exploring whether common combinations are worth
> defining for convenience.

Now that intersection types are a thing, I don't think combo interfaces are worth much here.  If anything, it would be just more impetus for type aliases to reduce typing.  (Human typing, I mean, not code typing.)

--Larry Garfield