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<div id="language.attributes.classes" class="sect1">
   <h2 class="title">Declaring Attribute Classes</h2>

   <p class="para">
    It is recommended to define a separate class for each attribute. In the simplest
    case, an empty class with the <code class="literal">#[Attribute]</code> declaration is sufficient.
    The attribute can be imported from the global namespace using a <code class="literal">use</code>
    statement.
   </p>

  <div class="example" id="example-432">
   <p><strong>Example #1 Simple Attribute Class</strong></p>

   <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">namespace </span><span style="color: #0000BB">Example</span><span style="color: #007700">;<br /><br />use </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">;<br /><br />#[</span><span style="color: #0000BB">Attribute</span><span style="color: #007700">]<br />class </span><span style="color: #0000BB">MyAttribute<br /></span><span style="color: #007700">{<br />}</span></span></code></div>
   </div>

  </div>

  <p class="para">
   To restrict the types of declarations an attribute can be applied to,
   pass a bitmask as the first argument to the <code class="literal">#[Attribute]</code>
   declaration.
  </p>

  <div class="example" id="example-433">
   <p><strong>Example #2 Using target specification to restrict where attributes can be used</strong></p>

   <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">namespace </span><span style="color: #0000BB">Example</span><span style="color: #007700">;<br /><br />use </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">;<br /><br />#[</span><span style="color: #0000BB">Attribute</span><span style="color: #007700">(</span><span style="color: #0000BB">Attribute</span><span style="color: #007700">::</span><span style="color: #0000BB">TARGET_METHOD </span><span style="color: #007700">| </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">::</span><span style="color: #0000BB">TARGET_FUNCTION</span><span style="color: #007700">)]<br />class </span><span style="color: #0000BB">MyAttribute<br /></span><span style="color: #007700">{<br />}</span></span></code></div>
    </div>


    <div class="example-contents"><p>
     Declaring <span class="classname"><strong class="classname">MyAttribute</strong></span> on another type will now throw an exception during
     the call to <span class="function"><a href="reflectionattribute.newinstance.php" class="function">ReflectionAttribute::newInstance()</a></span>
    </p></div>
   </div>

   <p class="para">The following targets can be specified:</p>
   
   <ul class="simplelist">
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-class">Attribute::TARGET_CLASS</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-function">Attribute::TARGET_FUNCTION</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-method">Attribute::TARGET_METHOD</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-property">Attribute::TARGET_PROPERTY</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-class-constant">Attribute::TARGET_CLASS_CONSTANT</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-parameter">Attribute::TARGET_PARAMETER</a></code></strong></li>
    <li><strong><code><a href="class.attribute.php#attribute.constants.target-all">Attribute::TARGET_ALL</a></code></strong></li>
   </ul>

   <p class="para">
    By default, an attribute can only be used once per declaration. To allow
    an attribute to be repeatable, specify it in the bitmask of the
    <code class="literal">#[Attribute]</code> declaration using the
    <strong><code><a href="class.attribute.php#attribute.constants.is-repeatable">Attribute::IS_REPEATABLE</a></code></strong> flag.
   </p>

   <div class="example" id="example-434">
    <p><strong>Example #3 Using IS_REPEATABLE to allow attribute on a declaration multiple times</strong></p>

    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">namespace </span><span style="color: #0000BB">Example</span><span style="color: #007700">;<br /><br />use </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">;<br /><br />#[</span><span style="color: #0000BB">Attribute</span><span style="color: #007700">(</span><span style="color: #0000BB">Attribute</span><span style="color: #007700">::</span><span style="color: #0000BB">TARGET_METHOD </span><span style="color: #007700">| </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">::</span><span style="color: #0000BB">TARGET_FUNCTION </span><span style="color: #007700">| </span><span style="color: #0000BB">Attribute</span><span style="color: #007700">::</span><span style="color: #0000BB">IS_REPEATABLE</span><span style="color: #007700">)]<br />class </span><span style="color: #0000BB">MyAttribute<br /></span><span style="color: #007700">{<br />}</span></span></code></div>
    </div>


   </div>
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