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</div><hr /><div id="language.oop5.decon" class="sect1">
<h2 class="title">Constructors and Destructors</h2>
<div class="sect2" id="language.oop5.decon.constructor">
<h3 class="title">Constructor</h3>
<div class="methodsynopsis dc-description" id="object.construct">
<span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>__construct</strong></span>
([ <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$args</code></span>
[, <span class="methodparam"> <code class="parameter">$...</code></span>
]] )</div>
<p class="para">
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>
<blockquote class="note"><p><strong class="note">Note</strong>:
<span class="simpara">
Parent constructors are not called implicitly if the child class defines
a constructor. In order to run a parent constructor, a call to
<span class="function"><strong>parent::__construct()</strong></span> within the child constructor is
required. If the child does not define a constructor then it may be inherited
from the parent class just like a normal class method (if it was not declared
as private).
</span>
</p></blockquote>
<div class="example" id="example-184">
<p><strong>Example #1 using new unified constructors</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">BaseClass </span><span style="color: #007700">{<br /> function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">() {<br /> print </span><span style="color: #DD0000">"In BaseClass constructor\n"</span><span style="color: #007700">;<br /> }<br />}<br /><br />class </span><span style="color: #0000BB">SubClass </span><span style="color: #007700">extends </span><span style="color: #0000BB">BaseClass </span><span style="color: #007700">{<br /> function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">() {<br /> </span><span style="color: #0000BB">parent</span><span style="color: #007700">::</span><span style="color: #0000BB">__construct</span><span style="color: #007700">();<br /> print </span><span style="color: #DD0000">"In SubClass constructor\n"</span><span style="color: #007700">;<br /> }<br />}<br /><br />class </span><span style="color: #0000BB">OtherSubClass </span><span style="color: #007700">extends </span><span style="color: #0000BB">BaseClass </span><span style="color: #007700">{<br /> </span><span style="color: #FF8000">// inherits BaseClass's constructor<br /></span><span style="color: #007700">}<br /><br /></span><span style="color: #FF8000">// In BaseClass constructor<br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= new </span><span style="color: #0000BB">BaseClass</span><span style="color: #007700">();<br /><br /></span><span style="color: #FF8000">// In BaseClass constructor<br />// In SubClass constructor<br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= new </span><span style="color: #0000BB">SubClass</span><span style="color: #007700">();<br /><br /></span><span style="color: #FF8000">// In BaseClass constructor<br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= new </span><span style="color: #0000BB">OtherSubClass</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<p class="para">
For backwards compatibility, if PHP 5 cannot find a
<a href="language.oop5.decon.html#object.construct" class="link">__construct()</a> function for a given class, and the
class did not inherit one from a parent 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
<a href="language.oop5.decon.html#object.construct" class="link">__construct()</a> which was used for different semantics.
</p>
<p class="para">
Unlike with other methods, PHP will not generate an
<strong><code>E_STRICT</code></strong> level error message when
<a href="language.oop5.decon.html#object.construct" class="link">__construct()</a> is overridden with different parameters
than the parent <a href="language.oop5.decon.html#object.construct" class="link">__construct()</a> method has.
</p>
<p class="para">
As of PHP 5.3.3, methods with the same name as the last element of a
namespaced class name will no longer be treated as constructor. This
change doesn't affect non-namespaced classes.
</p>
<div class="example" id="example-185">
<p><strong>Example #2 Constructors in namespaced classes</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">namespace </span><span style="color: #0000BB">Foo</span><span style="color: #007700">;<br />class </span><span style="color: #0000BB">Bar </span><span style="color: #007700">{<br /> public function </span><span style="color: #0000BB">Bar</span><span style="color: #007700">() {<br /> </span><span style="color: #FF8000">// treated as constructor in PHP 5.3.0-5.3.2<br /> // treated as regular method as of PHP 5.3.3<br /> </span><span style="color: #007700">}<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</div>
<div class="sect2" id="language.oop5.decon.destructor">
<h3 class="title">Destructor</h3>
<div class="methodsynopsis dc-description" id="object.destruct">
<span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>__destruct</strong></span>
( <span class="methodparam">void</span>
)</div>
<p class="para">
PHP 5 introduces a destructor concept similar to that of other
object-oriented languages, such as C++. The destructor method will be
called as soon as there are no other references to a particular object,
or in any order during the shutdown sequence.
</p>
<div class="example" id="example-186">
<p><strong>Example #3 Destructor Example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">MyDestructableClass </span><span style="color: #007700">{<br /> function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">() {<br /> print </span><span style="color: #DD0000">"In constructor\n"</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">= </span><span style="color: #DD0000">"MyDestructableClass"</span><span style="color: #007700">;<br /> }<br /><br /> function </span><span style="color: #0000BB">__destruct</span><span style="color: #007700">() {<br /> print </span><span style="color: #DD0000">"Destroying " </span><span style="color: #007700">. </span><span style="color: #0000BB">$this</span><span style="color: #007700">-></span><span style="color: #0000BB">name </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= new </span><span style="color: #0000BB">MyDestructableClass</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<p class="para">
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 <span class="function"><strong>parent::__destruct()</strong></span> in the destructor
body. Also like constructors, a child class may inherit the parent's
destructor if it does not implement one itself.
</p>
<p class="para">
The destructor will be called even if script execution is stopped using
<span class="function"><a href="function.exit.html" class="function">exit()</a></span>. Calling <span class="function"><a href="function.exit.html" class="function">exit()</a></span> in a destructor
will prevent the remaining shutdown routines from executing.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Destructors called during the script shutdown have HTTP headers already
sent. The working directory in the script shutdown phase can be different
with some SAPIs (e.g. Apache).
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Attempting to throw an exception from a destructor (called in the time of
script termination) causes a fatal error.
</p>
</p></blockquote>
</div>
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