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Remove ZEND_CHANGES and redirect all

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requests for that to zend-engine-2.php which is
a more up to date (and more visual) version of
the changes.

Also unify BC comments in error/index.php
This commit is contained in:
Gabor Hojtsy
2003-07-28 08:36:52 +00:00
parent e2c834c814
commit 97d3c56db0
2 changed files with 7 additions and 526 deletions
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518
ZEND_CHANGES.txt
View File

@@ -1,518 +0,0 @@
Changes in the Zend Engine 2.0
* New Object Model.
The Zend Engine's handling of objects has been completely
changed in order to allow for new features, but also to increase
its performance.
Objects were handled in previous versions like primitive types
(for instance integers and strings). The drawback of this method
is, that semantically the whole object was copied when a
variable was assigned or parameters were passed to a method. The
new approach refers to objects by handle and not by value (one
can think of a handle as an object's ID).
Many PHP programmers aren't even aware of the copying quirks of
the old object model and, therefore, there is a relatively good
chance that the amount of PHP applications that will work out of
the box or after a very small amount of modifications would be
high.
* Private Members.
The Zend Engine 2.0 introduces private member variables. Note
that for performance reasons no error message is emitted in
case of an illegal access to a private member variable.
Example:
<?php
class MyClass {
private $Hello = "Hello, World!\n";
function printHello() {
print $this->Hello;
}
}
class MyClass2 extends MyClass {
function printHello() {
MyClass::printHello(); /* Should print */
print $this->Hello; /* Shouldn't print out anything */
}
}
$obj = new MyClass();
print $obj->Hello; /* Shouldn't print out anything */
$obj->printHello(); /* Should print */
$obj = new MyClass2();
print $obj->Hello; /* Shouldn't print out anything */
$obj->printHello();
?>
* Object Cloning.
The Zend Engine 1.0 offered no way a user could decide what copy
constructor to run when an object is duplicated. During
duplication, the Zend Engine 1.0 did a bitwise copy making an
identical replica of all the object's properties.
Creating a copy of an object with fully replicated properties is
not always the wanted behavior. A good example of the need for
copy constructors, is if you have an object which represents a
GTK window and the object holds the resource of this GTK window,
when you create a duplicate you might want to create a new
window with the same properties and have the new object hold the
resource of the new window. Another example is if your object
holds a reference to another object which it uses and when you
replicate the parent object you want to create a new instance of
this other object so that the replica has its own separate copy.
An object copy is created by calling the object's __clone()
method.
Example:
<?php
$copy_of_object = $object->__clone();
?>
When the developer asks to create a new copy of an object, the
Zend Engine will check if a __clone() method has been defined or
not. If not, it will call a default __clone() which will copy
all of the object's properties. If a __clone() method is
defined, then it will be responsible to set the necessary
properties in the created object. For convenience, the engine
will supply a function that imports all of the properties from
the source object, so that they can start with a by-value
replica of the source object, and only override properties that
need to be changed. [The function hasn't been implemented yet]
Example:
<?php
class MyCloneable {
static $id = 0;
function MyCloneable() {
$this->id = self::$id++;
}
function __clone() {
$this->name = $clone->name;
$this->address = 'New York';
$this->id = self::$id++;
}
}
$obj = new MyCloneable();
$obj->name = 'Hello';
$obj->address = 'Tel-Aviv';
print $obj->id . "\n";
$obj = $obj->__clone();
print $obj->id . "\n";
print $obj->name . "\n";
print $obj->address . "\n";
?>
* Forced deletion of objects.
The Zend Engine 1.0 had no means to force deletion of an object
if there are still references to it. The newly introduced delete
statement calls the object's destructor and frees it even if the
object is referenced by some other places in the engine. Other
references to the deleted object become stale and trying to
access them results in a fatal error.
Note that if you have a user-defined function delete() in an old
script, this script will yield a parser error with the Zend
Engine 2.0, since 'delete' is now a reserved word.
* Nested classes (namespaces).
The Zend Engine 1.0 provided only three scopes: the global
scope, the class scope and the function scope. All scopes but
classes could contain variables, only the class and global
scopes could contain functions, while only the global scope
could contain constants and classes. This means that all of the
Zend Engine 1.0's scoping methods were inherently limited for
solving symbol name collision problems.
The Zend Engine 2.0 introduces the concept of nested classes
to solve the symbol collision problem by making it possible to
define multiple symbol tables able to contain all types of
symbols. The Zend Engine is aware of a current class,
defaulting to the global scope. Each class can contain it's
own set of constants, functions and static variables. In order
to access a class's local symbols you can use the self:: class
accessor, for example, you can do self::$my_static_name = "Hello".
You can also use the class's name such as
MyClass::$my_static_name = "Hello". WIth both constants and
functions, if you don't specify a class context the current class
will be searched first and if the search fails then the global
scope will be searched. If you want to force PHP to only check the
global scope you can use the main:: accessor. For example,
main::strlen() to make sure you're calling the strlen() in the main
scope. You will only need to worry about this if you are defining
methods which have the same name as global functions. For
constants you can use the same notation such as self::MY_CONSTANT
or main::MY_CONSTANT.
Sometimes you will not want to access constants, functions or classes
via the class accessor (i.e. MyClass::) because you use them very
often and are an extremely slow typist. In this case, you can import
functions, classes and constants from classes with the import keyword.
It's quite self explanatory and there are a few examples below.
* Classes may contain classes.
Example:
<?php
class DB::MySQL {
var $host = '';
function db_connect($user) {
print "Connecting to MySQL database '$this->host' as $user\n";
}
}
class DB::Oracle {
var $host = 'localhost';
function db_connect($user) {
print "Connecting to Oracle database '$this->host' as $user\n";
}
}
$MySQL_obj = new DB::MySQL();
$MySQL_obj->db_connect('Susan');
$Oracle_obj = new DB::Oracle();
$Oracle_obj->db_connect('Barbara');
?>
* Classes may contain constants.
Example:
<?php
class foo {
const hey = 'hello';
}
print foo::hey;
?>
* Current namespace's symbol tables are searched first for
constants and functions.
Example:
The following code prints "foobar", not "bar", because
the class constant overrides the "global" constant of
the same name.
<?php
define('foo', 'bar');
class FooClass {
const foo = 'foobar';
function printFoo() {
print foo;
}
}
?>
* In the scope of a function, the current namespace is that
of the containing class/namespace.
Example:
<?php
class FooClass {
function foo() {
$this->bar();
bar();
}
function bar() {
print "foobar\n";
}
}
$obj = new FooClass;
$obj->foo();
?>
This prints "foobar" two times, since a bar() method exists
in the current namespace.
* It is possible to "import" symbols from one namespace into
another.
Example:
<?php
class MyClass {
class MyClass2 {
function hello() {
print "Hello, World in MyClass2\n";
}
}
function hello() {
print "Hello, World\n";
}
}
import function hello, class MyClass2 from MyClass;
MyClass2::hello();
hello();
?>
Example:
<?php
class MyOuterClass {
class MyInnerClass {
function func1() {
print "func1()\n";
}
function func2() {
print "func2()\n";
}
}
}
import class * from MyOuterClass;
import function func2 from MyOuterClass::MyInnerClass;
MyInnerClass::func1();
func2();
?>
Example:
<?php
class MyOuterClass {
const Hello = "Hello, World\n";
}
import const Hello from MyOuterClass;
print Hello;
?>
Old code that does not take advantage of namespaces will run
without modifications.
* Unified Constructors.
The Zend Engine allows developers to declare constructor methods
for classes. Classes which have a constructor method call this
method on each newly-created object, so it is suitable for any
initialization that the object may need before it can be used.
With the Zend Engine 1.0, constructor methods were class methods
that had the same name as the class itself. Since it is very
common to call parent constructors from derived classes, the way
the Zend Engine 1.0 worked made it a bit cumbersome to move
classes around in a large class hierarchy. If a class is moved
to reside under a different parent, the constructor name of that
parent changes as well, and the code in the derived class that
calls the parent constructor has to be modified.
The Zend Engine 2.0 introduces a standard way of declaring
constructor methods by calling them by the name __construct().
Example:
<?php
class BaseClass {
function __construct() {
print "In BaseClass constructor\n";
}
}
class SubClass extends BaseClass {
function __construct() {
parent::__construct();
print "In SubClass constructor\n";
}
}
$obj = new BaseClass();
$obj = new SubClass();
?>
For backwards compatibility, if the Zend Engine 2.0 cannot find
a __construct() function for a given class, it will search for
the old-style constructor function, by the name of the class.
Effectively, it means that the only case that would have
compatibility issues is if the class had a method named
__construct() which was used for different semantics.
* Destructors.
Having the ability to define destructors for objects can be very
useful. Destructors can log messages for debugging, close
database connections and do other clean-up work.
No mechanism for object destructors existed in the Zend Engine
1.0, although PHP had already support for registering functions
which should be run on request shutdown.
The Zend Engine 2.0 introduces a destructor concept similar to
that of other object-oriented languages, such as Java: When the
last reference to an object is destroyed the object's
destructor, which is a class method name __destruct() that
recieves no parameters, is called before the object is freed
from memory.
Example:
<?php
class MyDestructableClass {
function __construct() {
print "In constructor\n";
$this->name = 'MyDestructableClass';
}
function __destruct() {
print 'Destroying ' . $this->name . "\n";
}
}
$obj = new MyDestructableClass();
?>
Like constructors, parent destructors will not be called
implicitly by the engine. In order to run a parent destructor,
one would have to explicitly call parent::__destruct() in the
destructor body.
* Exceptions.
The Zend Engine 1.0 had no exception handling. The Zend Engine 2.0
introduces a exception model similar to that of other programming
languages.
Example:
<?php
class MyException {
function __construct($exception) {
$this->exception = $exception;
}
function Display() {
print "MyException: $this->exception\n";
}
}
class MyExceptionFoo extends MyException {
function __construct($exception) {
$this->exception = $exception;
}
function Display() {
print "MyException: $this->exception\n";
}
}
try {
throw new MyExceptionFoo('Hello');
}
catch (MyException $exception) {
$exception->Display();
}
?>
Old code that has no user-defined functions 'catch', 'throw' and
'try' will run without modifications.
* Dereferencing objects returned from functions.
Example:
<?php
class Circle {
function draw() {
print "Circle\n";
}
}
class Square {
function draw() {
print "Square\n";
}
}
function ShapeFactoryMethod($shape) {
switch ($shape) {
case 'Circle': return new Circle();
case 'Square': return new Square();
}
}
ShapeFactoryMethod('Circle')->draw();
ShapeFactoryMethod('Square')->draw();
?>
* Static member variables of static classes can now be
initialized.
Example:
<?php
class foo {
static $my_static = 5;
}
print foo::$my_static;
?>
* Parameters that are passed by reference to a function
may now have default values.
Example:
<?php
function my_function(&$var = null) {
if ($var === null) {
die('$var needs to have a value');
}
}
?>
* Built-In Backtracing.
Example:
<?php
$backtrace = debug_backtrace();
foreach ($backtrace as $step) {
$class = isset($step['class']) ? $step['class'] . '::' : '';
printf(
"%s%s [%s:%s]\n",
$class,
$step['function'],
$step['file'],
$step['line']
);
}
?>

15
error/index.php
View File

@@ -138,8 +138,6 @@ $uri_aliases = array (
"subscribe" => "mailing-lists",
"logos" => "download-logos",
"README.mirror" => "mirroring", // backward compatibility
# manual shortcuts
"ini" => "configuration",
@@ -159,19 +157,20 @@ $uri_aliases = array (
"gd" => "image",
"tut" => "tutorial",
"tut.php" => "tutorial", // for backward compatibility with PHP page!
"tut.php" => "tutorial", // BC
"faq.php" => "faq", // for backward compatibility with PHP page!
"bugs.php" => "bugs", // for backward compatibility with PHP page!
"bugstats.php" => "bugstats", // for backward compatibility with PHP page!
"faq.php" => "faq", // BC
"bugs.php" => "bugs", // BC
"bugstats.php" => "bugstats", // BC
"icap" => "mcal", // mcal is the successor of icap
"README.mirror" => "mirroring", // BC with mirroring readme!
"README.mirror" => "mirroring", // BC
"ZEND_CHANGES.txt" => "zend-engine-2.php", // BC
# external shortcut aliases ;)
"dochowto" => "phpdochowto",
"projects.php" => "projects", // for backward compatibility with PHP page!
"projects.php" => "projects", // BC
);
$external_redirects = array(