Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:27931
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain hotmail.com designates 65.54.246.210 as permitted sender)
Message-ID: <BAY126-W17996A5AB81CDC44CA8EDDA29C0@phx.gbl>
Content-Type: multipart/alternative;
	boundary="_a11e5699-f669-4b44-b8c0-83a127c90f31_"
To: <internals@lists.php.net>
Date: Fri, 9 Feb 2007 04:02:57 +0300
Importance: Normal
MIME-Version: 1.0
Subject: RE: [PHP-DEV] Suggestion: global variables being accessed in local
 scope
From: guilhermeblanco@hotmail.com (Guilherme Blanco)

--_a11e5699-f669-4b44-b8c0-83a127c90f31_
Content-Type: text/plain; charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable

Brian,I am sorry about the message indentation... Seems PHP-Internals list =
does not like M$ Live(r) Mail! roflI wrote it carefully indented... =3D\I=
=0A=
read your extension messages, but you idea was different from mine.=0A=
What you suggested in that post is exactly what runkit does today.My=0A=
idea is a little bit different. If possible, the idea is something like=0A=
this (sorry, but my C skill are not so good and I'll write in Java):I extra=
cted the source from a Krakatoa compiler I wrote (Krakatoa =3D> C)...Curren=
tly, PHP tries to access a local variable usage/assignment with this (Compi=
ler class scope):// Retrieve variable from local scopeVariable v =3D (Varia=
ble ) this.symbolTable.getInLocal( this.lexer.getStringValue() );if ( v =3D=
=3D null ) {    // Variable does not exist in local scope, throw a fatal er=
ror.    this.error.show("FATAL ERROR: Undefined Variable " + this.lexer.get=
StringValue(), CompilerError.FATAL_ERROR);}The best approach that I suggest=
ed eliminates the need of global keyword and also the $GLOBALS autoglobal a=
rray.The source code I have to do what I suggest is this:// Retrieve variab=
le from local scope=0A=
Variable v =3D (Variable ) this.symbolTable.getInLocal( this.lexer.getStrin=
gValue() );=0A=
=0A=
if ( v =3D=3D null ) {    // Try to retrieve the variable from global scope=
    v =3D (Variable ) this.symbolTable.getInGlobal( this.lexer.getStringVal=
ue() );        if ( v =3D=3D null ) {        // Variable does not exist in =
local nor in global scope, throw a fatal error.=0A=
        this.error.show("FATAL ERROR: Undefined Variable " + this.lexer.get=
StringValue(), CompilerError.FATAL_ERROR);    }=0A=
}As=0A=
you can see, the only change needed is in a throw-able error (Undefined=0A=
variable), which does a second look-up in the symbolTable.Doing=0A=
this, you do not need to use $GLOBALS nevermore! And also, global can=0A=
be extinct too, since the compiler recognizes the variable in global=0A=
scope alone.I know the PHP source is not well commented and=0A=
structured, but I think this is not an impossible change to be done,=0A=
and will bring a lot of benefits to all PHP developers.I wish God come here=
 and make my message indented until it reaches the PHP-Internals list.... =
=3DDBest regards,Guilherme Blanco - Web Developer=0A=
CBC - Certified Bindows Consultant=0A=
Cell Phone: +55 (16) 9166-6902=0A=
URL: http://blog.bisna.com=0A=
MSN: guilhermeblanco@hotmail.com=0A=
S=E3o Carlos - SP/Brazil> Date: Thu, 8 Feb 2007 12:07:23 -0600> From: brian=
m@dealnews.com> To: guilhermeblanco@hotmail.com> CC: internals@lists.php.ne=
t> Subject: Re: [PHP-DEV] Suggestion: global variables being accessed in lo=
cal scope> > Well, this was a little hard to read, but, let me see if I und=
erstand > one thing.  You would have PHP look in the local scope and then a=
lso in > the global scope?  If so, I would never support that idea.  I reme=
mber > an email from Rasmus about why PHP's scoping is the way it is. > Som=
ething to do with chasing down a scope issue in a C app for days.> > I wrot=
e an extension to do this about 4 years ago.  I submitted it to > the, then=
 pear-dev list.> > http://marc.theaimsgroup.com/?l=3Dpear-dev&m=3D104534556=
711383&w=3D2> > It was not received well, so I did not pursue it.  To see a=
ll the > replies look at > http://marc.theaimsgroup.com/?l=3Dpear-dev&w=3D2=
&r=3D48&s=3DNew+PHP+extension&q=3Db > and read the ones titled "New PHP Ext=
ension".  MARC did not thread the > discussion well.> > My extension did no=
t have a function, but required php.ini settings to > declare the variable =
names.  It also required they start with and under > score if I remember co=
rrectly.> > Now the bad news.  The code was lost in a hard drive crash.  I =
am not > sure it would work now though.  I am sure a lot has changed in 4 y=
ears.> > > Guilherme Blanco wrote:> > Hello PHP maintainers,During this wee=
k, I spoke with Sara Golemon about the possibility to change one current be=
havior of PHP.My first suggestion, as you can see in my blog post: http://b=
log.bisna.com/archives/32#comments was a new function called register_super=
global.While talking with her, I found that it'll be easier to be implement=
ed another thing.Currently, when we deal with objects and functions in a PH=
P application, to access most common variables, we have to do one of these =
things:function m() {    global $DB; // ...}Another one:function m() {    $=
DB =3D Database::getInstance();  // ...}Or:function m() {    $DB =3D Regist=
ry::get("DB");  // ...}And finally... via Factory:function m() {    $DB =3D=
 Env::getDatabaseConnection();  // ...}We can also specify via runkit a sup=
erglobal variable (DB), and use it.While all those solutions have some cost=
s, maybe there is a possibility to change the structure and simplify all th=
ose lines of code.As I already said, my first idea was a > function, regist=
er_superglobal, which you register it and access it in a local scope withou=
t using none of the examples I listed.Sara told me about superglobals and e=
tc, but I suggested her about the possibility to change the idea a little. =
Here is the comment I describe 2 possible ideas:"The perfect behavior shoul=
d be (inside a function), if a variable> > does not exist, try to access a =
global (without doing via $GLOBALS or> > global). If it doesn=92t exist in =
the second try, then throw a fatal> > error. With this, you do not need to =
think in superglobal variable or> > anything else. Maybe this suggestion is=
 currently too much difficult to achieve.> > The workaround can be done usi=
ng normal variables. But, as I> > mentioned before, when the statement uses=
 a variable, it checks for the> > local variables declarations hash table; =
the idea is different here=85 if> > the variable does not exist in local, l=
ook in the hash table I> > mentioned (which stores the subscribed variables=
 to behavior like> > superglobal) and, if found, grab the variable from the=
 global variable> > declarations hash table.> > As you can see, there will =
be only one performance impact (in normal> > variable), doing a hash table =
checking. You do not need to change> > autoglobal or static variables. In a=
n average system, the needed time> > to do this checking will be an advanta=
ge than the currently best> > approach (Registry). You lose in one side, bu=
t receive more in the> > other."She agreed with my idea ("That=92s all doab=
le, and with autoglobals being CVs now, it=92s even doable> > without too m=
uch performance impact on the global fetches themselves=85"), BUT she said =
I will have to convince engine team to accept this idea too. Also, she said=
 that will be a too much added complexity for too little. I disagree with h=
er, since currently there are much more processment retrieving one object f=
rom a Registry or using a global accessor than another compiler hash checki=
ng. The performance impact is almost irrelevant (cannot be measured) and th=
e final solution is cleaner than all the others. If you look at real world =
large applications, you can experience these workarounds. And, as I checked=
 with my contact list (around 600), it'll be a great improvement of PHP.Now=
 I am leaving this suggestion to internals list, and I hope you look affect=
ionately at it.Best regards,Guilherme Blanco - Web Developer> > CBC - Certi=
fied Bindows Consultant> > Cell Phone: +55 (16) 9166-6902> > URL: http://bl=
og.bisna.com> > MSN: guilhermeblanco@hotmail.com> > S=E3o Carlos - SP/Brazi=
l> > _________________________________________________________________> > O=
 Windows Live Spaces est=E1 aqui! Descubra como =E9 f=E1cil criar seu espa=
=E7o na Web e sua rede amigos.> > http://spaces.live.com/signup.aspx> > -- =
> > Brian Moon> -------------> http://dealnews.com/> It's good to be cheap =
=3D)> > -- > PHP Internals - PHP Runtime Development Mailing List> To unsub=
scribe, visit: http://www.php.net/unsub.php>=20
_________________________________________________________________
Ligue para os seus amigos gr=E1tis. Fa=E7a chamadas de PC-para-PC pelo mess=
enger-- GR=C1TIS
http://get.live.com/messenger/overview=

--_a11e5699-f669-4b44-b8c0-83a127c90f31_--