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>Manual PHP</TH
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><A
HREF="migration5.databases.html"
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>Înapoi</A
></TD
><TD
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ALIGN="center"
VALIGN="bottom"
>Anexa B. Migrating from PHP 4 to PHP 5</TD
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HREF="migrating5.errorrep.html"
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><DIV
CLASS="section"
><H1
CLASS="section"
><A
NAME="migration5.oop"
>New Object Model</A
></H1
><P
> In PHP 5 there is a new Object Model. PHP's handling of objects has been
completely rewritten, allowing for better performance and more features.
In previous versions of PHP, objects were handled like primitive types
(for instance integers and strings). The drawback of this method was that
semantically the whole object was copied when a variable was assigned, or
pass as a parameter to a method. In the new approach, objects are
referenced by handle, and not by value (one can think of a handle as an
object's identifier).
</P
><P
> Many PHP programmers aren't even aware of the copying quirks of the old
object model and, therefore, the majority of PHP applications will work
out of the box, or with very few modifications.
</P
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration.oop.members"
>Private and Protected Members</A
></H2
><P
> PHP 5 introduces private and protected member variables, they allow you
to define the visibility of class properties.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132385"
></A
><P
><B
>Exemplu B-4. Private and Protected Members accesibility</B
></P
><P
> Protected member variables can be accessed in classes extending the
class they are declared in, whereas private member variables can only be
accessed by the class they belong to.
</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyClass </font><font color="#007700">{<br /> </font><font color="#0000BB">private $Hello </font><font color="#007700">= </font><font color="#DD0000">"Hello, World!\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">protected $Bar </font><font color="#007700">= </font><font color="#DD0000">"Hello, Foo!\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">protected $Foo </font><font color="#007700">= </font><font color="#DD0000">"Hello, Bar!\n"</font><font color="#007700">;<br /><br /> function </font><font color="#0000BB">printHello</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"MyClass::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Hello</font><font color="#007700">;<br /> print </font><font color="#DD0000">"MyClass::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Bar</font><font color="#007700">;<br /> print </font><font color="#DD0000">"MyClass::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Foo</font><font color="#007700">;<br /> }<br />}<br /><br />class </font><font color="#0000BB">MyClass2 </font><font color="#007700">extends </font><font color="#0000BB">MyClass </font><font color="#007700">{<br /> </font><font color="#0000BB">protected $Foo</font><font color="#007700">;<br /> <br /> function </font><font color="#0000BB">printHello</font><font color="#007700">() {<br /> </font><font color="#0000BB">MyClass</font><font color="#007700">::</font><font color="#0000BB">printHello</font><font color="#007700">(); </font><font color="#FF8000">/* Should print */<br /> </font><font color="#007700">print </font><font color="#DD0000">"MyClass2::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Hello</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /> </font><font color="#007700">print </font><font color="#DD0000">"MyClass2::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Bar</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print (not declared)*/<br /> </font><font color="#007700">print </font><font color="#DD0000">"MyClass2::printHello() " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">Foo</font><font color="#007700">; </font><font color="#FF8000">/* Should print */<br /> </font><font color="#007700">}<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">MyClass</font><font color="#007700">();<br />print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Hello</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#007700">print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Bar</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#007700">print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Foo</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">printHello</font><font color="#007700">(); </font><font color="#FF8000">/* Should print */<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">MyClass2</font><font color="#007700">();<br />print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Hello</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#007700">print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Bar</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#007700">print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">Foo</font><font color="#007700">; </font><font color="#FF8000">/* Shouldn't print out anything */<br /></font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">printHello</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration.oop.methods"
>Private and Protected Methods</A
></H2
><P
> With PHP 5, private and protected methods are also introduced.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132392"
></A
><P
><B
>Exemplu B-5. Protected methods example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">private </font><font color="#007700">function </font><font color="#0000BB">aPrivateMethod</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"Foo::aPrivateMethod() called.\n"</font><font color="#007700">;<br /> }<br /><br /> </font><font color="#0000BB">protected </font><font color="#007700">function </font><font color="#0000BB">aProtectedMethod</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"Foo::aProtectedMethod() called.\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">aPrivateMethod</font><font color="#007700">();<br /> }<br />}<br /><br />class </font><font color="#0000BB">Bar </font><font color="#007700">extends </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">aPublicMethod</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"Bar::aPublicMethod() called.\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">aProtectedMethod</font><font color="#007700">();<br /> }<br />}<br /><br /></font><font color="#0000BB">$o </font><font color="#007700">= new </font><font color="#0000BB">Bar</font><font color="#007700">;<br /></font><font color="#0000BB">$o</font><font color="#007700">-></font><font color="#0000BB">aPublicMethod</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Old code that has no user-defined classes or functions named
"public", "protected" or "private" should
run without modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration.oop.abstract"
>Abstract Classes and Methods</A
></H2
><P
> PHP 5 also introduces abstract classes and methods. An abstract method
only declares the method's signature and does not provide an
implementation. A class that contains abstract methods needs to be
declared abstract.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132399"
></A
><P
><B
>Exemplu B-6. Abstract class example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br />abstract </font><font color="#007700">class </font><font color="#0000BB">AbstractClass </font><font color="#007700">{<br /> </font><font color="#0000BB">abstract public </font><font color="#007700">function </font><font color="#0000BB">test</font><font color="#007700">();<br />}<br /><br />class </font><font color="#0000BB">ImplementedClass </font><font color="#007700">extends </font><font color="#0000BB">AbstractClass </font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">test</font><font color="#007700">() {<br /> echo </font><font color="#DD0000">"ImplementedClass::test() called.\n"</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$o </font><font color="#007700">= new </font><font color="#0000BB">ImplementedClass</font><font color="#007700">;<br /></font><font color="#0000BB">$o</font><font color="#007700">-></font><font color="#0000BB">test</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Abstract classes cannot be instantiated. Old code that has no
user-defined classes or functions named 'abstract' should run without
modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration.oop.interfaces"
>Interfaces</A
></H2
><P
> PHP 5 introduces interfaces. A class may implement an arbitrary list of
interfaces.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132406"
></A
><P
><B
>Exemplu B-7. Interface example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br />interface Throwable </font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">getMessage</font><font color="#007700">();<br />}<br /><br />class </font><font color="#0000BB">MyException implements Throwable </font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">function </font><font color="#0000BB">getMessage</font><font color="#007700">() {<br /> </font><font color="#FF8000">// ...<br /> </font><font color="#007700">}<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Old code that has no user-defined classes or functions named 'interface'
or 'implements' should run without modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration.oop.typehints"
>Class Type Hints</A
></H2
><P
> While remaining loosely typed PHP 5 introduces the ability to use class
type hints to declare the expected class of objects that are passed as
parameters to a method.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132413"
></A
><P
><B
>Exemplu B-8. Class type hinting example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br />interface Foo </font><font color="#007700">{<br /> function </font><font color="#0000BB">a</font><font color="#007700">(</font><font color="#0000BB">Foo $foo</font><font color="#007700">);<br />}<br /><br /></font><font color="#0000BB">interface Bar </font><font color="#007700">{<br /> function </font><font color="#0000BB">b</font><font color="#007700">(</font><font color="#0000BB">Bar $bar</font><font color="#007700">);<br />}<br /><br />class </font><font color="#0000BB">FooBar implements Foo</font><font color="#007700">, </font><font color="#0000BB">Bar </font><font color="#007700">{<br /> function </font><font color="#0000BB">a</font><font color="#007700">(</font><font color="#0000BB">Foo $foo</font><font color="#007700">) {<br /> </font><font color="#FF8000">// ...<br /> </font><font color="#007700">}<br /><br /> function </font><font color="#0000BB">b</font><font color="#007700">(</font><font color="#0000BB">Bar $bar</font><font color="#007700">) {<br /> </font><font color="#FF8000">// ...<br /> </font><font color="#007700">}<br />}<br /><br /></font><font color="#0000BB">$a </font><font color="#007700">= new </font><font color="#0000BB">FooBar</font><font color="#007700">;<br /></font><font color="#0000BB">$b </font><font color="#007700">= new </font><font color="#0000BB">FooBar</font><font color="#007700">;<br /><br /></font><font color="#0000BB">$a</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">(</font><font color="#0000BB">$b</font><font color="#007700">);<br /></font><font color="#0000BB">$a</font><font color="#007700">-></font><font color="#0000BB">b</font><font color="#007700">(</font><font color="#0000BB">$b</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> These class type hints are not checked upon compilation, as would be the
case in a typed language, but during runtime. This means that:
</P
><DIV
CLASS="informalexample"
><P
></P
><A
NAME="AEN132417"
></A
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">foo</font><font color="#007700">(</font><font color="#0000BB">ClassName $object</font><font color="#007700">) {<br /> </font><font color="#FF8000">// ...<br /></font><font color="#007700">}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
></P
></DIV
><P
>is equivalent to:</P
><DIV
CLASS="informalexample"
><P
></P
><A
NAME="AEN132420"
></A
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">foo</font><font color="#007700">(</font><font color="#0000BB">$object</font><font color="#007700">) {<br /> if (!(</font><font color="#0000BB">$object instanceof ClassName</font><font color="#007700">)) {<br /> die(</font><font color="#DD0000">"Argument 1 must be an instance of ClassName"</font><font color="#007700">);<br /> }<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.final"
>final</A
></H2
><P
> PHP 5 introduces the "final" keyword to declare final members and
methods. Methods and members declared final cannot be overridden by
sub-classes.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132425"
></A
><P
><B
>Exemplu B-9. final method</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">final </font><font color="#007700">function </font><font color="#0000BB">bar</font><font color="#007700">() {<br /> </font><font color="#FF8000">// ...<br /> </font><font color="#007700">}<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> It is furthermore possible to make a class final. Doing this prevents a
class from being specialized (it cannot be inherited by another class).
There's no need to declare the methods of a final class themselves as
final.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132429"
></A
><P
><B
>Exemplu B-10. final class</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br />final </font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#FF8000">// class definition<br /></font><font color="#007700">}<br /><br /></font><font color="#FF8000">// the next line is impossible<br />// class Bork extends Foo {}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Properties can not be final.
</P
><P
> Old code that has no user-defined classes or functions named 'final'
should run without modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.cloning"
>Objects Cloning</A
></H2
><P
> PHP 4 offered no way a user could decide what copy constructor to run
when an object is duplicated. During duplication, PHP 4 did a bit for bit
copy making an identical replica of all the object's properties.
</P
><P
> 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.
</P
><P
> An object copy is created by using the clone keyword (which calls the
object's <B
CLASS="function"
>__clone()</B
> method if possible). An object's
<B
CLASS="function"
>__clone()</B
> method cannot be called directly.
</P
><P
> When the developer asks to create a new copy of an object, PHP 5 will
check if a <B
CLASS="function"
>__clone()</B
> 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 <B
CLASS="function"
>__clone()</B
> 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.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132444"
></A
><P
><B
>Exemplu B-11. Objects cloning</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyCloneable </font><font color="#007700">{<br /> static </font><font color="#0000BB">$id </font><font color="#007700">= </font><font color="#0000BB">0</font><font color="#007700">;<br /><br /> function </font><font color="#0000BB">MyCloneable</font><font color="#007700">() {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">id </font><font color="#007700">= </font><font color="#0000BB">self</font><font color="#007700">::</font><font color="#0000BB">$id</font><font color="#007700">++;<br /> }<br /><br /> function </font><font color="#0000BB">__clone</font><font color="#007700">() {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">address </font><font color="#007700">= </font><font color="#DD0000">"New York"</font><font color="#007700">;<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">id </font><font color="#007700">= </font><font color="#0000BB">self</font><font color="#007700">::</font><font color="#0000BB">$id</font><font color="#007700">++;<br /> }<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">MyCloneable</font><font color="#007700">();<br /><br /></font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">name </font><font color="#007700">= </font><font color="#DD0000">"Hello"</font><font color="#007700">;<br /></font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">address </font><font color="#007700">= </font><font color="#DD0000">"Tel-Aviv"</font><font color="#007700">;<br /><br />print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">id </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /><br /></font><font color="#0000BB">$obj_cloned </font><font color="#007700">= </font><font color="#0000BB">clone $obj</font><font color="#007700">;<br /><br />print </font><font color="#0000BB">$obj_cloned</font><font color="#007700">-></font><font color="#0000BB">id </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br />print </font><font color="#0000BB">$obj_cloned</font><font color="#007700">-></font><font color="#0000BB">name </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br />print </font><font color="#0000BB">$obj_cloned</font><font color="#007700">-></font><font color="#0000BB">address </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.constructors"
>Constructors</A
></H2
><P
> PHP 5 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 is used.
</P
><P
> With PHP 4, 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 PHP 4 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.
</P
><P
> PHP 5 introduces a standard way of declaring constructor methods by
calling them by the name <B
CLASS="function"
>__construct()</B
>.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132453"
></A
><P
><B
>Exemplu B-12. using new unified constructors</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">BaseClass </font><font color="#007700">{<br /> function </font><font color="#0000BB">__construct</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"In BaseClass constructor\n"</font><font color="#007700">;<br /> }<br />}<br /><br />class </font><font color="#0000BB">SubClass </font><font color="#007700">extends </font><font color="#0000BB">BaseClass </font><font color="#007700">{<br /> function </font><font color="#0000BB">__construct</font><font color="#007700">() {<br /> </font><font color="#0000BB">parent</font><font color="#007700">::</font><font color="#0000BB">__construct</font><font color="#007700">();<br /> print </font><font color="#DD0000">"In SubClass constructor\n"</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">BaseClass</font><font color="#007700">();<br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">SubClass</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> For backwards compatibility, if PHP 5 cannot find a
<B
CLASS="function"
>__construct()</B
> 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
<B
CLASS="function"
>__construct()</B
> which was used for different semantics.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.destructors"
>Destructors</A
></H2
><P
> 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 PHP 4, although PHP had already support for registering functions
which should be run on request shutdown.
</P
><P
> PHP 5 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
named <B
CLASS="function"
>__destruct()</B
> that receives no parameters, is
called before the object is freed from memory.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132464"
></A
><P
><B
>Exemplu B-13. Destructor</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">MyDestructableClass </font><font color="#007700">{<br /> function </font><font color="#0000BB">__construct</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"In constructor\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">name </font><font color="#007700">= </font><font color="#DD0000">"MyDestructableClass"</font><font color="#007700">;<br /> }<br /><br /> function </font><font color="#0000BB">__destruct</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"Destroying " </font><font color="#007700">. </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">name </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">MyDestructableClass</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> 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 <B
CLASS="function"
>parent::__destruct()</B
> in the destructor
body.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.constants"
>Constants</A
></H2
><P
> PHP 5 introduces per-class constants:
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132472"
></A
><P
><B
>Exemplu B-14. Class constant example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> const </font><font color="#0000BB">constant </font><font color="#007700">= </font><font color="#DD0000">"constant"</font><font color="#007700">;<br />}<br /><br />echo </font><font color="#DD0000">"Foo::constant = " </font><font color="#007700">. </font><font color="#0000BB">Foo</font><font color="#007700">::</font><font color="#0000BB">constant </font><font color="#007700">. </font><font color="#DD0000">"\n"</font><font color="#007700">;<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Old code that has no user-defined classes or functions named 'const'
will run without modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.exceptions"
>Exceptions</A
></H2
><P
> PHP 4 had no exception handling. PHP 5 introduces a exception model
similar to that of other programming languages. Note that there is
support for "catch all" but not for the "finally" clause.
</P
><P
> Exceptions can be rethrown in catch blocks. Also it is possible to have
multiple catch blocks. In that case the caught exception is compared with
the classtype of each catch block from top to bottom and the first block
that has an 'instanceof' match gets executed. When the catch block
finishes, execution continues at the end of the last catch block. If no
catch block has an 'instanceof' match then the next try/catch block is
searched until no more try/catch blocks are available. In that case the
exception is an uncaught exception and the program terminates with
showing the exception.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132480"
></A
><P
><B
>Exemplu B-15. Exception creation example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br />try </font><font color="#007700">{<br /> </font><font color="#0000BB">throw </font><font color="#007700">new </font><font color="#0000BB">Exception</font><font color="#007700">(</font><font color="#DD0000">'Hello'</font><font color="#007700">);<br />}<br /></font><font color="#0000BB">catch </font><font color="#007700">(</font><font color="#0000BB">Exception $exception</font><font color="#007700">) {<br /> echo </font><font color="#0000BB">$exception</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Old code that has no user-defined classes or functions 'catch', 'throw'
and 'try' will run without modifications.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.dereferencing"
>Dereferencing objects returned from functions</A
></H2
><P
> In PHP 4 it wasn't possible to dereference objects returned by functions
and make further method calls on those objects. With PHP 5, the following
is now possible:
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132487"
></A
><P
><B
>Exemplu B-16. Dereferencing example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Circle </font><font color="#007700">{<br /> function </font><font color="#0000BB">draw</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"Circle\n"</font><font color="#007700">;<br /> }<br />}<br /> <br />class </font><font color="#0000BB">Square </font><font color="#007700">{<br /> function </font><font color="#0000BB">draw</font><font color="#007700">() {<br /> print </font><font color="#DD0000">"Square\n"</font><font color="#007700">;<br /> }<br />}<br /><br />function </font><font color="#0000BB">ShapeFactoryMethod</font><font color="#007700">(</font><font color="#0000BB">$shape</font><font color="#007700">) {<br /> switch (</font><font color="#0000BB">$shape</font><font color="#007700">) {<br /> case </font><font color="#DD0000">"Circle"</font><font color="#007700">:<br /> return new </font><font color="#0000BB">Circle</font><font color="#007700">();<br /> case </font><font color="#DD0000">"Square"</font><font color="#007700">:<br /> return new </font><font color="#0000BB">Square</font><font color="#007700">();<br /> }<br />}<br /><br /></font><font color="#0000BB">ShapeFactoryMethod</font><font color="#007700">(</font><font color="#DD0000">"Circle"</font><font color="#007700">)-></font><font color="#0000BB">draw</font><font color="#007700">();<br /></font><font color="#0000BB">ShapeFactoryMethod</font><font color="#007700">(</font><font color="#DD0000">"Square"</font><font color="#007700">)-></font><font color="#0000BB">draw</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.staticinit"
>Static member variables initialization</A
></H2
><P
> Static member variables of static classes can now be initialized.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132493"
></A
><P
><B
>Exemplu B-17. Static variable initialization example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">foo </font><font color="#007700">{<br /> static </font><font color="#0000BB">$my_static </font><font color="#007700">= </font><font color="#0000BB">5</font><font color="#007700">;<br /> </font><font color="#0000BB">public $my_prop </font><font color="#007700">= </font><font color="#DD0000">'bla'</font><font color="#007700">;<br />}<br /><br />print </font><font color="#0000BB">foo</font><font color="#007700">::</font><font color="#0000BB">$my_static</font><font color="#007700">;<br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">foo</font><font color="#007700">;<br />print </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">my_prop</font><font color="#007700">;<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.staticmethods"
>Static Methods</A
></H2
><P
> PHP 5 introduces the 'static' keyword to declare a method static, thus
callable from outside the object context.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132499"
></A
><P
><B
>Exemplu B-18. Static Methods example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">public </font><font color="#007700">static function </font><font color="#0000BB">aStaticMethod</font><font color="#007700">() {<br /> </font><font color="#FF8000">// ...<br /> </font><font color="#007700">}<br />}<br /><br /></font><font color="#0000BB">Foo</font><font color="#007700">::</font><font color="#0000BB">aStaticMethod</font><font color="#007700">();<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> The pseudo variable $this is not available inside a method that has been
declared static.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.instanceof"
>instanceof</A
></H2
><P
> PHP 5 introduces the <VAR
CLASS="literal"
>instanceof</VAR
> keyword, that
allows you to ascertain whether or not an object is an instance of
a class, or extends a class, or implements an interface.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132507"
></A
><P
><B
>Exemplu B-19. <VAR
CLASS="literal"
>instanceof</VAR
> example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">baseClass </font><font color="#007700">{ }<br /><br /></font><font color="#0000BB">$a </font><font color="#007700">= new </font><font color="#0000BB">baseClass</font><font color="#007700">;<br /><br />if (</font><font color="#0000BB">$a instanceof baseClass</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"Hello World"</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.staticvars"
>Static function variables</A
></H2
><P
> Statics are now treated at compile-time which allows developers to
assign variables to statics by reference. This change also greatly
improves their performance but means that indirect references to statics
will not work anymore.
</P
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.refparams"
>Parameters passed by reference</A
></H2
><P
> Parameters that are passed by reference to a function may now have
default values
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132517"
></A
><P
><B
>Exemplu B-20. </B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">my_function</font><font color="#007700">(&</font><font color="#0000BB">$var </font><font color="#007700">= </font><font color="#0000BB">null</font><font color="#007700">) {<br /> if (</font><font color="#0000BB">$var </font><font color="#007700">=== </font><font color="#0000BB">null</font><font color="#007700">) {<br /> die(</font><font color="#DD0000">"$var needs to have a value"</font><font color="#007700">);<br /> }<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.autoload"
><B
CLASS="function"
>__autoload()</B
></A
></H2
><P
> The <B
CLASS="function"
>__autoload()</B
> interceptor function will be
automatically called when an undeclared class is to be instantiated.
The name of that class will be passed to the <B
CLASS="function"
>__autoload()</B
>
interceptor function as its only argument.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132526"
></A
><P
><B
>Exemplu B-21. <B
CLASS="function"
>__autoload()</B
> example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">__autoload</font><font color="#007700">(</font><font color="#0000BB">$className</font><font color="#007700">) {<br /> include_once </font><font color="#0000BB">$className </font><font color="#007700">. </font><font color="#DD0000">".php"</font><font color="#007700">;<br />}<br /><br /></font><font color="#0000BB">$object </font><font color="#007700">= new </font><font color="#0000BB">ClassName</font><font color="#007700">;<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.overload"
>Overloadable Method calls and Property accesses</A
></H2
><P
> Both method calls and property accesses can be overloaded via the
<B
CLASS="function"
>__call()</B
>, <B
CLASS="function"
>__get()</B
> and
<B
CLASS="function"
>__set()</B
> methods.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132536"
></A
><P
><B
>Exemplu B-22.
<B
CLASS="function"
>__get()</B
> and
<B
CLASS="function"
>__set()</B
>
</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Setter </font><font color="#007700">{<br /> </font><font color="#0000BB">public $n</font><font color="#007700">;<br /> </font><font color="#0000BB">public $x </font><font color="#007700">= array(</font><font color="#DD0000">"a" </font><font color="#007700">=> </font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#DD0000">"b" </font><font color="#007700">=> </font><font color="#0000BB">2</font><font color="#007700">, </font><font color="#DD0000">"c" </font><font color="#007700">=> </font><font color="#0000BB">3</font><font color="#007700">);<br /><br /> function </font><font color="#0000BB">__get</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"Getting </font><font color="#007700">[</font><font color="#DD0000">$nm</font><font color="#007700">]\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> if (isset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">])) {<br /> </font><font color="#0000BB">$r </font><font color="#007700">= </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">];<br /> print </font><font color="#DD0000">"Returning: $r</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> return </font><font color="#0000BB">$r</font><font color="#007700">;<br /> } else {<br /> print </font><font color="#DD0000">"Nothing!\n"</font><font color="#007700">;<br /> }<br /> }<br /><br /> function </font><font color="#0000BB">__set</font><font color="#007700">(</font><font color="#0000BB">$nm</font><font color="#007700">, </font><font color="#0000BB">$val</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"Setting </font><font color="#007700">[</font><font color="#DD0000">$nm</font><font color="#007700">]</font><font color="#DD0000"> to $val</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /><br /> if (isset(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">])) {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">[</font><font color="#0000BB">$nm</font><font color="#007700">] = </font><font color="#0000BB">$val</font><font color="#007700">;<br /> print </font><font color="#DD0000">"OK!\n"</font><font color="#007700">;<br /> } else {<br /> print </font><font color="#DD0000">"Not OK!\n"</font><font color="#007700">;<br /> }<br /> }<br />}<br /><br /><br /></font><font color="#0000BB">$foo </font><font color="#007700">= new </font><font color="#0000BB">Setter</font><font color="#007700">();<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">n </font><font color="#007700">= </font><font color="#0000BB">1</font><font color="#007700">;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a </font><font color="#007700">= </font><font color="#0000BB">100</font><font color="#007700">;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">a</font><font color="#007700">++;<br /></font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">z</font><font color="#007700">++;<br /></font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$foo</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132541"
></A
><P
><B
>Exemplu B-23. <B
CLASS="function"
>__get()</B
> example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Caller </font><font color="#007700">{<br /> </font><font color="#0000BB">private $x </font><font color="#007700">= array(</font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#0000BB">2</font><font color="#007700">, </font><font color="#0000BB">3</font><font color="#007700">);<br /><br /> function </font><font color="#0000BB">__call</font><font color="#007700">(</font><font color="#0000BB">$m</font><font color="#007700">, </font><font color="#0000BB">$a</font><font color="#007700">) {<br /> print </font><font color="#DD0000">"Method $m called:</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br /> </font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">);<br /> return </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">x</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$foo </font><font color="#007700">= new </font><font color="#0000BB">Caller</font><font color="#007700">();<br /></font><font color="#0000BB">$a </font><font color="#007700">= </font><font color="#0000BB">$foo</font><font color="#007700">-></font><font color="#0000BB">test</font><font color="#007700">(</font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#DD0000">"2"</font><font color="#007700">, </font><font color="#0000BB">3.4</font><font color="#007700">, </font><font color="#0000BB">true</font><font color="#007700">);<br /></font><font color="#0000BB">var_dump</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migration5.oop.iteration"
>Iteration</A
></H2
><P
> Objects may be iterated in an overloaded way when used with foreach. The
default behavior is to iterate over all properties.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132548"
></A
><P
><B
>Exemplu B-24. Object iteration example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">public $x </font><font color="#007700">= </font><font color="#0000BB">1</font><font color="#007700">;<br /> </font><font color="#0000BB">public $y </font><font color="#007700">= </font><font color="#0000BB">2</font><font color="#007700">;<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">Foo</font><font color="#007700">;<br /><br />foreach (</font><font color="#0000BB">$obj </font><font color="#007700">as </font><font color="#0000BB">$prp_name </font><font color="#007700">=> </font><font color="#0000BB">$prop_value</font><font color="#007700">) {<br /> </font><font color="#FF8000">// using the property<br /></font><font color="#007700">}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
><P
> Each class whose instances can be iterated with foreach should implement
the empty interface <VAR
CLASS="literal"
>Traversable</VAR
>. Hence any object that
says it implements <VAR
CLASS="literal"
>Traversable</VAR
> can be used with foreach.
</P
><P
> The interfaces <VAR
CLASS="literal"
>IteratorAggregate</VAR
> and <VAR
CLASS="literal"
>Iterator</VAR
>
allows you to specify how class objects are iterated in PHP code. The first
of them simply has a method <B
CLASS="function"
>getIterator()</B
> which must
return an array or an object that either implements the interface
<VAR
CLASS="literal"
>Iterator</VAR
> or is instantiated from an internal
class that can be iterated
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132559"
></A
><P
><B
>Exemplu B-25. Iterator creation example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">ObjectIterator implements Iterator </font><font color="#007700">{<br /><br /> </font><font color="#0000BB">private $obj</font><font color="#007700">;<br /> </font><font color="#0000BB">private $num</font><font color="#007700">;<br /><br /> function </font><font color="#0000BB">__construct</font><font color="#007700">(</font><font color="#0000BB">$obj</font><font color="#007700">) {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">obj </font><font color="#007700">= </font><font color="#0000BB">$obj</font><font color="#007700">;<br /> }<br /> function </font><font color="#0000BB">rewind</font><font color="#007700">() {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num </font><font color="#007700">= </font><font color="#0000BB">0</font><font color="#007700">;<br /> }<br /> function </font><font color="#0000BB">valid</font><font color="#007700">() {<br /> return </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num </font><font color="#007700">< </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">obj</font><font color="#007700">-></font><font color="#0000BB">max</font><font color="#007700">;<br /> }<br /> function </font><font color="#0000BB">key</font><font color="#007700">() {<br /> return </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num</font><font color="#007700">;<br /> }<br /> function </font><font color="#0000BB">current</font><font color="#007700">() {<br /> switch(</font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num</font><font color="#007700">) {<br /> case </font><font color="#0000BB">0</font><font color="#007700">: return </font><font color="#DD0000">"1st"</font><font color="#007700">;<br /> case </font><font color="#0000BB">1</font><font color="#007700">: return </font><font color="#DD0000">"2nd"</font><font color="#007700">;<br /> case </font><font color="#0000BB">2</font><font color="#007700">: return </font><font color="#DD0000">"3rd"</font><font color="#007700">;<br /> default: return </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num</font><font color="#007700">.</font><font color="#DD0000">"th"</font><font color="#007700">;<br /> }<br /> }<br /> function </font><font color="#0000BB">next</font><font color="#007700">() {<br /> </font><font color="#0000BB">$this</font><font color="#007700">-></font><font color="#0000BB">num</font><font color="#007700">++;<br /> }<br />}<br /><br />class </font><font color="#0000BB">Object implements IteratorAggregate </font><font color="#007700">{<br /><br /> </font><font color="#0000BB">public $max </font><font color="#007700">= </font><font color="#0000BB">3</font><font color="#007700">;<br /><br /> function </font><font color="#0000BB">getIterator</font><font color="#007700">() {<br /> return new </font><font color="#0000BB">ObjectIterator</font><font color="#007700">(</font><font color="#0000BB">$this</font><font color="#007700">);<br /> }<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">Object</font><font color="#007700">;<br /><br /></font><font color="#FF8000">// this foreach ...<br /></font><font color="#007700">foreach(</font><font color="#0000BB">$obj </font><font color="#007700">as </font><font color="#0000BB">$key </font><font color="#007700">=> </font><font color="#0000BB">$val</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"$key = $val</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br />}<br /><br /></font><font color="#FF8000">// matches the following 7 lines with the for directive.<br /></font><font color="#0000BB">$it </font><font color="#007700">= </font><font color="#0000BB">$obj</font><font color="#007700">-></font><font color="#0000BB">getIterator</font><font color="#007700">();<br />for(</font><font color="#0000BB">$it</font><font color="#007700">-></font><font color="#0000BB">rewind</font><font color="#007700">(); </font><font color="#0000BB">$it</font><font color="#007700">-></font><font color="#0000BB">valid</font><font color="#007700">(); </font><font color="#0000BB">$it</font><font color="#007700">-></font><font color="#0000BB">next</font><font color="#007700">()) {<br /> </font><font color="#0000BB">$key </font><font color="#007700">= </font><font color="#0000BB">$it</font><font color="#007700">-></font><font color="#0000BB">current</font><font color="#007700">();<br /> </font><font color="#0000BB">$val </font><font color="#007700">= </font><font color="#0000BB">$it</font><font color="#007700">-></font><font color="#0000BB">key</font><font color="#007700">();<br /> echo </font><font color="#DD0000">"$key = $val</font><font color="#007700">\n</font><font color="#DD0000">"</font><font color="#007700">;<br />}<br />unset(</font><font color="#0000BB">$it</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migrating5.oop.methodconst"
><VAR
CLASS="literal"
>__METHOD__</VAR
> constant</A
></H2
><P
> The new <VAR
CLASS="literal"
>__METHOD__</VAR
> pseudo constant shows the current
class and method when used inside a method and the function when used outside
of a class.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132567"
></A
><P
><B
>Exemplu B-26. <VAR
CLASS="literal"
>__METHOD__</VAR
> use example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> function </font><font color="#0000BB">show</font><font color="#007700">() {<br /> echo </font><font color="#0000BB">__METHOD__</font><font color="#007700">;<br /> }<br />}<br /><br />class </font><font color="#0000BB">Bar </font><font color="#007700">extends </font><font color="#0000BB">Foo </font><font color="#007700">{<br />}<br /><br /></font><font color="#0000BB">Foo</font><font color="#007700">::</font><font color="#0000BB">show</font><font color="#007700">(); </font><font color="#FF8000">// outputs Foo::show<br /></font><font color="#0000BB">Bar</font><font color="#007700">::</font><font color="#0000BB">show</font><font color="#007700">(); </font><font color="#FF8000">// outputs Foo::show either since __METHOD__ is<br /> // compile-time evaluated token<br /><br /></font><font color="#007700">function </font><font color="#0000BB">test</font><font color="#007700">() {<br /> echo </font><font color="#0000BB">__METHOD__</font><font color="#007700">;<br />}<br /><br /></font><font color="#0000BB">test</font><font color="#007700">(); </font><font color="#FF8000">// outputs test<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migrating5.oop.tostring"
><B
CLASS="function"
>__toString()</B
> method</A
></H2
><P
> The new <B
CLASS="function"
>__toString()</B
> magic method allows you to
overload the object to string conversion.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132576"
></A
><P
><B
>Exemplu B-27. <B
CLASS="function"
>__toString()</B
> example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> function </font><font color="#0000BB">__toString</font><font color="#007700">() {<br /> return </font><font color="#DD0000">"What ever"</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">$obj </font><font color="#007700">= new </font><font color="#0000BB">Foo</font><font color="#007700">;<br /><br />echo </font><font color="#0000BB">$obj</font><font color="#007700">; </font><font color="#FF8000">// call __toString()<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="section"
><H2
CLASS="section"
><A
NAME="migrating5.oop.reflection"
>Reflection API</A
></H2
><P
> PHP 5 comes with a complete reflection API that adds the ability to
reverse-engineer classes, interfaces, functions and methods as well as
extensions.
</P
><P
> The reflection API also offers ways of getting doc comments for
functions, classes and methods.
</P
><P
> Nearly all aspects of object oriented code can be reflected by using the
reflection API which is
<A
HREF="http://sitten-polizei.de/php/reflection_api/docs/language.reflection.html"
TARGET="_top"
> documented separately</A
>.
</P
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN132586"
></A
><P
><B
>Exemplu B-28. Reflection API use example</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">class </font><font color="#0000BB">Foo </font><font color="#007700">{<br /> </font><font color="#0000BB">public $prop</font><font color="#007700">;<br /> function </font><font color="#0000BB">Func</font><font color="#007700">(</font><font color="#0000BB">$name</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"Hello $name"</font><font color="#007700">;<br /> }<br />}<br /><br /></font><font color="#0000BB">reflectionClass</font><font color="#007700">::</font><font color="#0000BB">export</font><font color="#007700">(</font><font color="#DD0000">'Foo'</font><font color="#007700">);<br /></font><font color="#0000BB">reflectionObject</font><font color="#007700">::</font><font color="#0000BB">export</font><font color="#007700">(new </font><font color="#0000BB">Foo</font><font color="#007700">);<br /></font><font color="#0000BB">reflectionMethod</font><font color="#007700">::</font><font color="#0000BB">export</font><font color="#007700">(</font><font color="#DD0000">'Foo'</font><font color="#007700">, </font><font color="#DD0000">'func'</font><font color="#007700">);<br /></font><font color="#0000BB">reflectionProperty</font><font color="#007700">::</font><font color="#0000BB">export</font><font color="#007700">(</font><font color="#DD0000">'Foo'</font><font color="#007700">, </font><font color="#DD0000">'prop'</font><font color="#007700">);<br /></font><font color="#0000BB">reflectionExtension</font><font color="#007700">::</font><font color="#0000BB">export</font><font color="#007700">(</font><font color="#DD0000">'standard'</font><font color="#007700">);<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="migration5.databases.html"
ACCESSKEY="P"
>Înapoi</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Acasã</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="migrating5.errorrep.html"
ACCESSKEY="N"
>Înainte</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Databases</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="migration5.html"
ACCESSKEY="U"
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></TD
><TD
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VALIGN="top"
>Error Reporting</TD
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