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To: Stas Malyshev <smalyshev@sugarcrm.com>
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Date: Fri, 16 Aug 2013 01:57:03 +0200
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Subject: Re: [PHP-DEV] [RFC] Constant Scalar Expressions
From: johannes@schlueters.de (Johannes =?ISO-8859-1?Q?Schl=FCter?=)

On Thu, 2013-08-15 at 16:42 -0700, Stas Malyshev wrote:
> Hi!
> 
> > Though obv, in reality we wouldn't use runkit_constant_add(), it'd be a
> > new opcode which had the same effect.  This is basically transparent to
> > opcode caches, allows the constant to actually change based on runtime
> 
> If the class definition can actually change at runtime, I think it'd
> make it much harder for opcode caches since they can't any longer assume
> class definition can't change at any random place in the code.
> 
> But this is not the most tricky part. The most tricky part is this:
> 
> 
> if(true) return;
> class Foo {
> const halfpie = M_PI/2;
> }
> 
> Now what happens if this is implemented as an opcode? We can't run any
> opcodes past return statement, but Foo is expected to be defined here.

note that we have this functionality already:

$ php -r 'class A { const C = FOO; } define("FOO", 23); echo A::C;'
23

The first fetch will resolve that.
If we add "constant scalar expression" this has to work for class
constants, too. Else we add crazy new inconsistencies to the language.

johannes