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Date: Thu, 28 Apr 2016 11:11:24 -0400
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To: Josh Di Fabio <joshdifabio@gmail.com>
Cc: Levi Morrison <levim@php.net>, internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Intersection Types
From: guilhermeblanco@gmail.com ("guilhermeblanco@gmail.com")

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Nice!

I've read the RFC and there's only one missing thing that is either
undocumented or missed during patch creation: instanceof.
I'd be amazing if we could do: $foo instanceof Foo & Bar

Cheers,

On Thu, Apr 28, 2016 at 5:00 AM, Josh Di Fabio <joshdifabio@gmail.com>
wrote:

> On Thu, Apr 28, 2016 at 4:54 AM, Levi Morrison <levim@php.net> wrote:
> > Internals,
> >
> > As alluded to last week I have another RFC for improving the type
> > system: [intersection types][1].
> >
> > It allows parameters to define multiple type constraints that must be
> > satisfied. Common combinations of our built-in types include
> > `ArrayAccess & Traversable & Countable` and `Countable & Iterator`.
> >
> > Some people have suggest I merge this and union types into one RFC.
> > For now I'll just proceed with them separately to gain feedback.
> >
> >   [1]: http://wiki.php.net/rfc/intersection_types
> >
> > --
> > PHP Internals - PHP Runtime Development Mailing List
> > To unsubscribe, visit: http://www.php.net/unsub.php
> >
>
> To me, it seems that intersection types are more useful than union
> types (other than the obvious null|Foo and array|Traversable cases) as
> they'd allow us to write smaller interfaces and better follow ISP in
> userland, with interfaces becoming much more convenient for
> documenting the requirements of a parameter.
>
> At present we tend to have incomplete implementations of interfaces
> (e.g. throw OperationNotSupportedException). Union types would allow
> us to create more, smaller interfaces and avoid situations where the
> type of a parameter doesn't accurately reflect the method's true
> requirements, or where concretions are incomplete implementations of
> an interface.
>
> Thanks for your efforts, Levi, I'm excited about this one!
>
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>
>


-- 
Guilherme Blanco
Lead Architect at E-Block

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