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</div><hr /><div id="language.oop5.properties" class="sect1">
<h2 class="title">Properties</h2>
<p class="para">
Class member variables are called "properties". You may also see
them referred to using other terms such as "attributes" or
"fields", but for the purposes of this reference we will use
"properties". They are defined by using one of the
keywords <em>public</em>, <em>protected</em>,
or <em>private</em>, followed by a normal variable
declaration. This declaration may include an initialization, but
this initialization must be a constant value--that is, it must be
able to be evaluated at compile time and must not depend on
run-time information in order to be evaluated.
</p>
<p class="para">
See <a href="language.oop5.visibility.html" class="xref">Visibility</a> for more
information on the meanings
of <em>public</em>, <em>protected</em>,
and <em>private</em>.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
In order to maintain backward compatibility with PHP 4, PHP 5 will
still accept the use of the keyword <em>var</em> in
property declarations instead of (or in addition
to) <em>public</em>, <em>protected</em>,
or <em>private</em>. However, <em>var</em> is
no longer required. In versions of PHP from 5.0 to 5.1.3, the use
of <em>var</em> was considered deprecated and would
issue an <strong><code>E_STRICT</code></strong> warning, but since PHP
5.1.3 it is no longer deprecated and does not issue the warning.
</p>
<p class="para">
If you declare a property using <em>var</em> instead of
one of <em>public</em>, <em>protected</em>,
or <em>private</em>, then PHP 5 will treat the property
as if it had been declared as <em>public</em>.
</p>
</p></blockquote>
<p class="para">
Within class methods non-static properties may be accessed by using
<em>-></em> (Object Operator): <var class="varname"><var class="varname">$this->property</var></var>
(where <em>property</em> is the name of the property).
Static properties are accessed by using the <em>::</em> (Double Colon):
<var class="varname"><var class="varname">self::$property</var></var>. See <a href="language.oop5.static.html" class="link">Static Keyword</a>
for more information on the difference between static and non-static properties.
</p>
<p class="para">
The pseudo-variable <var class="varname"><var class="varname">$this</var></var> is available inside
any class method when that method is called from within an object
context. <var class="varname"><var class="varname">$this</var></var> is a reference to the calling
object (usually the object to which the method belongs, but
possibly another object, if the method is called
<a href="language.oop5.static.html" class="link">statically</a> from the context
of a secondary object).
</p>
<p class="para">
<div class="example" id="example-176">
<p><strong>Example #1 property declarations</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">SimpleClass<br /></span><span style="color: #007700">{<br /> </span><span style="color: #FF8000">// invalid property declarations:<br /> </span><span style="color: #007700">public </span><span style="color: #0000BB">$var1 </span><span style="color: #007700">= </span><span style="color: #DD0000">'hello ' </span><span style="color: #007700">. </span><span style="color: #DD0000">'world'</span><span style="color: #007700">;<br /> public </span><span style="color: #0000BB">$var2 </span><span style="color: #007700">= <<<EOD<br /></span><span style="color: #DD0000">hello world<br /></span><span style="color: #007700">EOD;<br /> public </span><span style="color: #0000BB">$var3 </span><span style="color: #007700">= </span><span style="color: #0000BB">1</span><span style="color: #007700">+</span><span style="color: #0000BB">2</span><span style="color: #007700">;<br /> public </span><span style="color: #0000BB">$var4 </span><span style="color: #007700">= </span><span style="color: #0000BB">self</span><span style="color: #007700">::</span><span style="color: #0000BB">myStaticMethod</span><span style="color: #007700">();<br /> public </span><span style="color: #0000BB">$var5 </span><span style="color: #007700">= </span><span style="color: #0000BB">$myVar</span><span style="color: #007700">;<br /><br /> </span><span style="color: #FF8000">// valid property declarations:<br /> </span><span style="color: #007700">public </span><span style="color: #0000BB">$var6 </span><span style="color: #007700">= </span><span style="color: #0000BB">myConstant</span><span style="color: #007700">;<br /> public </span><span style="color: #0000BB">$var7 </span><span style="color: #007700">= array(</span><span style="color: #0000BB">true</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">// This is allowed only in PHP 5.3.0 and later.<br /> </span><span style="color: #007700">public </span><span style="color: #0000BB">$var8 </span><span style="color: #007700">= <<<'EOD'<br /></span><span style="color: #DD0000">hello world<br /></span><span style="color: #007700">EOD;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
There are some nice functions to handle classes and objects. You
might want to take a look at
the <a href="ref.classobj.html" class="link">Class/Object Functions</a>.
</p>
</p></blockquote>
<p class="para">
Unlike
<a href="language.types.string.html#language.types.string.syntax.heredoc" class="link">heredocs</a>,
<a href="language.types.string.html#language.types.string.syntax.nowdoc" class="link">nowdocs</a>
can be used in any static data context, including property
declarations.
<div class="example" id="example-177">
<p><strong>Example #2 Example of using a nowdoc to initialize a property</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">foo </span><span style="color: #007700">{<br /> </span><span style="color: #FF8000">// As of PHP 5.3.0<br /> </span><span style="color: #007700">public </span><span style="color: #0000BB">$bar </span><span style="color: #007700">= <<<'EOT'<br /></span><span style="color: #DD0000">bar<br /></span><span style="color: #007700">EOT;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Nowdoc support was added in PHP 5.3.0.
</p>
</p></blockquote>
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