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Date: Sat, 19 Nov 2016 16:49:16 +0000
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Subject: Re: [PHP-DEV] [RFC][Vote] Typed Properties
From: rowan.collins@gmail.com (Rowan Collins)

On 19/11/2016 14:04, Rasmus Schultz wrote:
> lack of features
> and consistency [...] where these features were engineered
> into the language from the design stage, rather than being added on a bit
> at a time.

I think the consistency and "engineered in" parts of this are more 
important than people give them credit for. Adding type hints to a 
dynamic language is not a trivial thing; what do those type hints 
actually *mean*?

> He actually had something like "public int $id" in a class-declaration on
> his screen, and was genuinely confused - he simply assumed that would work

What did he expect that declaration to do? Did he expect his program not 
to compile if he wrote some code that assigned a string? Did he expect 
to have to run a static analysis tool to detect errors? Did he expect 
the run-time to insert an assertion on every assignment and raise a 
runtime error? Did he expect this to happen even in production, or only 
in a development-only "checked" mode? All of these are possible 
behaviours, implemented in other languages.

I've written some of my thoughts on how it *could* work in this blog 
post: http://rwec.co.uk/q/php-type-system

Before we add type hints anywhere else in the language, I think we need 
to think about what we are actually working towards. Otherwise, we're 
going to end up with a mess of inconsistent rules because each set of 
type hints was added separately with slightly different semantics and 
caveats.

Regards,

-- 
Rowan Collins
[IMSoP]