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Date: Wed, 14 Aug 2013 12:52:12 +0200
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To: Anthony Ferrara <ircmaxell@gmail.com>
Cc: Stas Malyshev <smalyshev@sugarcrm.com>, 
	"internals@lists.php.net" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Constant Scalar Expressions
From: jpauli@php.net (Julien Pauli)

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On Wed, Aug 14, 2013 at 12:44 PM, Anthony Ferrara <ircmaxell@gmail.com>wrote:

> Stas,
>
>
> On Wed, Aug 14, 2013 at 5:01 AM, Stas Malyshev <smalyshev@sugarcrm.com>wrote:
>
>> Hi!
>>
>> >> https://wiki.php.net/rfc/const_scalar_expressions
>>
>> I like the idea, but absence of constant support makes this thing much
>> less useful, as you can't do things like:
>>
>> public $angle = M_PI/2;
>>
>> I think this is one of the reasons this idea was never implemented -
>> because without constant support you're limited to doing things that are
>> quite obvious and trivial.
>>
>
> Yeah, having constants in those expressions would be great. If only
> constants in PHP were actually constant...
>
> But this win is really cheap (a trivial change to the parser), so I
> figured it was worth proposing separately. If we want to add the opcode
> stream later to do expressions for constant values, we can. This just gives
> us the quick win today of allowing relatively trivial, but important
> expressions.
>
> The biggest wins I see are in power-of-2 math:
>

I agree !


>
> class Foo {
>     const FLAG_1 = 1 << 0;
>     const FLAG_2 = 1 << 1;
>     const FLAG_3 = 1 << 2;
>     const FLAG_4 = 1 << 3;
>     const FLAG_5 = 1 << 4;
>     const FLAG_6 = 1 << 5;
>     const FLAG_7 = 1 << 6;
> }
>
>
Julien

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