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Subject: Re: [PHP-DEV] PHP Language Specification
From: ivan.enderlin@hoa-project.net ("Ivan Enderlin @ Hoa")


On 23/07/2014 22:59, Ben Ramsey wrote:
> This got me thinking about the whole version number debate. With a lang=
uage specification, to what does the version number refer? The state of t=
he language specification, or the state of a given implementation of the =
specification? Right now, the number refers to the state of the PHP Group=
 implementation, and implementations like HippyVM and HHVM say that they =
are compatible with Zend PHP 5.x. Will we version the language specificat=
ion separately, and individual releases of various implementations (inclu=
ding the PHP Group implementation) will state that they are compatible wi=
th version X of the specification?
This is exactly what I said in =93a lot of questions remain open=94 in my=
=20
previous mail [1]. Taking the example of XML, CSS, HTML, ECMAScript or=20
other languages (maybe the JVM, I don't know exactly), there is version=20
numbers for the specification, that are different of the version numbers =

of the implementations. Even more, the version of the implementations is =

most of the time unknown (what is the version of SpiderMonkey or V8 for=20
ECMAScript x? We don't really know).

In the case of PHP, this is different because the word =93PHP=94 was=20
previously (yes, it's done) representing the language **and** the=20
implementation. Consequently, we can't start with PHP1.

1. A solution would be to start with PHP6 (and 7, I don't know=85) for th=
e=20
specification, and then, the version of the implementations will have no =

importance (HHVM1.3, ZendEngine3.0, whatever you want).
2. Another solution is to refer to the PHP version with a =93new name=94,=
=20
something like =93PHPx=94 or =93PHPv=94, so we will have "PHPx1=94, =93PH=
Px2=94 etc.
3. A final solution I see is to refer to PHP with =93PHP1=94 which will b=
e=20
equivalent to =93PHP6.1=94, exactly as Java7 which is in reality Java1.7,=
=20
but when they will introduce Java2.x, they will encounter a problem=85

My favorite solution is the 2nd one.

Moreover, what about (let's say with PHPx) PHPx1.2.3? Does it make sense =

to have x.y.z for a language specification? We don't see it very often.=20
Actually, x.y is enough I would say (XML1.1, Java1.7 etc.), I don't know =

any x.y.z language specification.

Another problem to solve: what about the `php_version` function, the=20
`PHP_VERSION_ID` constant etc. If an implementation (a VM) respects the=20
specification, testing the version of the specification does not make=20
sense anymore, except in edge-cases, so we will really test the version=20
of language. Do we keep these functions and constants? Do we introduce=20
new ones? The specification might define the format of some  functions=20
or constants to get the versions of the implementation, for example:=20
`PHP_VM_VERSION_ID` along with `PHP_VM_NAME` (something similar to what=20
PHP does with SAPI).

Thoughts?


[1] http://marc.info/?l=3Dphp-internals&m=3D140612071919140&w=3D2

--=20
Ivan Enderlin
Developer of Hoa
http://hoa-project.net/

PhD. at DISC/Femto-ST (Vesontio) and INRIA (Cassis)
http://disc.univ-fcomte.fr/ and http://www.inria.fr/

Member of HTML and WebApps Working Group of W3C
http://w3.org/