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<h2 class="title">Name resolution rules</h2>
<p class="verinfo">(PHP 5 >= 5.3.0)</p>
<p class="para">
For the purposes of these resolution rules, here are some important definitions:
<dl>
<strong class="title">Namespace name definitions</strong>
<dt>
<span class="term">Unqualified name</span>
<dd>
<p class="para">
This is an identifier without a namespace separator, such as <em>Foo</em>
</p>
</dd>
</dt>
<dt>
<span class="term">Qualified name</span>
<dd>
<p class="para">
This is an identifier with a namespace separator, such as <em>Foo\Bar</em>
</p>
</dd>
</dt>
<dt>
<span class="term">Fully qualified name</span>
<dd>
<p class="para">
This is an identifier with a namespace separator that begins with a
namespace separator, such as <em>\Foo\Bar</em>. The namespace
<em>\Foo</em> is also a fully qualified name.
</p>
</dd>
</dt>
</dl>
</p>
<p class="para">
Names are resolved following these resolution rules:
<ol type="1">
<li class="listitem">
<span class="simpara">
Calls to fully qualified functions, classes or constants are resolved at compile-time.
For instance <em>new \A\B</em> resolves to class <em>A\B</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
All unqualified and qualified names (not fully qualified names) are translated during
compilation according to current
import rules. For example, if the namespace <em>A\B\C</em> is imported as
<em>C</em>, a call to
<em>C\D\e()</em> is translated to <em>A\B\C\D\e()</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Inside a namespace, all qualified names not translated according to import
rules have the current namespace prepended. For example, if a call
to <em>C\D\e()</em> is performed within namespace <em>A\B</em>,
it is translated to <em>A\B\C\D\e()</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Unqualified class names are translated during compilation according to current
import rules (full name substituted for short imported name). In example, if
the namespace <em>A\B\C</em> is imported as C, <em>new C()</em> is
translated to <em>new A\B\C()</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
Inside namespace (say A\B), calls to unqualified functions are resolved at run-time.
Here is how a
call to function <em>foo()</em> is resolved:
</span>
<ol type="1">
<li class="listitem">
<span class="simpara">
It looks for a function from the current namespace:
<em>A\B\foo()</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
It tries to find and call the <em class="emphasis">global</em> function
<em>foo()</em>.
</span>
</li>
</ol>
</li>
<li class="listitem">
<span class="simpara">
Inside namespace (say <em>A\B</em>), calls to unqualified or qualified
class names (not fully qualified class names)
are resolved at run-time. Here is how a call to
<em>new C()</em> or <em>new D\E()</em> is resolved.
For <em> new C()</em>:
</span>
<ol type="1">
<li class="listitem">
<span class="simpara">
It looks for a class from the current namespace:
<em>A\B\C</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
It attempts to autoload <em>A\B\C</em>.
</span>
</li>
</ol>
<span class="simpara">
For <em> new D\E()</em>:
</span>
<ol type="1">
<li class="listitem">
<span class="simpara">
It looks for a class by prepending the current namespace:
<em>A\B\D\E</em>.
</span>
</li>
<li class="listitem">
<span class="simpara">
It attempts to autoload <em>A\B\D\E</em>.
</span>
</li>
</ol>
<span class="simpara">
To reference any global class in the global namespace,
its fully qualified name <em>new \C()</em> must be used.
</span>
</li>
</ol>
</p>
<div class="example" id="example-257">
<p><strong>Example #1 Name resolutions illustrated</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">A</span><span style="color: #007700">;<br />use </span><span style="color: #0000BB">B</span><span style="color: #007700">\</span><span style="color: #0000BB">D</span><span style="color: #007700">, </span><span style="color: #0000BB">C</span><span style="color: #007700">\</span><span style="color: #0000BB">E </span><span style="color: #007700">as </span><span style="color: #0000BB">F</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// function calls<br /><br /></span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// first tries to call "foo" defined in namespace "A"<br /> // then calls global function "foo"<br /><br /></span><span style="color: #007700">\</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls function "foo" defined in global scope<br /><br /></span><span style="color: #0000BB">my</span><span style="color: #007700">\</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls function "foo" defined in namespace "A\my"<br /><br /></span><span style="color: #0000BB">F</span><span style="color: #007700">(); </span><span style="color: #FF8000">// first tries to call "F" defined in namespace "A"<br /> // then calls global function "F"<br /><br />// class references<br /><br /></span><span style="color: #007700">new </span><span style="color: #0000BB">B</span><span style="color: #007700">(); </span><span style="color: #FF8000">// creates object of class "B" defined in namespace "A"<br /> // if not found, it tries to autoload class "A\B"<br /><br /></span><span style="color: #007700">new </span><span style="color: #0000BB">D</span><span style="color: #007700">(); </span><span style="color: #FF8000">// using import rules, creates object of class "D" defined in namespace "B"<br /> // if not found, it tries to autoload class "B\D"<br /><br /></span><span style="color: #007700">new </span><span style="color: #0000BB">F</span><span style="color: #007700">(); </span><span style="color: #FF8000">// using import rules, creates object of class "E" defined in namespace "C"<br /> // if not found, it tries to autoload class "C\E"<br /><br /></span><span style="color: #007700">new \</span><span style="color: #0000BB">B</span><span style="color: #007700">(); </span><span style="color: #FF8000">// creates object of class "B" defined in global scope<br /> // if not found, it tries to autoload class "B"<br /><br /></span><span style="color: #007700">new \</span><span style="color: #0000BB">D</span><span style="color: #007700">(); </span><span style="color: #FF8000">// creates object of class "D" defined in global scope<br /> // if not found, it tries to autoload class "D"<br /><br /></span><span style="color: #007700">new \</span><span style="color: #0000BB">F</span><span style="color: #007700">(); </span><span style="color: #FF8000">// creates object of class "F" defined in global scope<br /> // if not found, it tries to autoload class "F"<br /><br />// static methods/namespace functions from another namespace<br /><br /></span><span style="color: #0000BB">B</span><span style="color: #007700">\</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls function "foo" from namespace "A\B"<br /><br /></span><span style="color: #0000BB">B</span><span style="color: #007700">::</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls method "foo" of class "B" defined in namespace "A"<br /> // if class "A\B" not found, it tries to autoload class "A\B"<br /><br /></span><span style="color: #0000BB">D</span><span style="color: #007700">::</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// using import rules, calls method "foo" of class "D" defined in namespace "B"<br /> // if class "B\D" not found, it tries to autoload class "B\D"<br /><br /></span><span style="color: #007700">\</span><span style="color: #0000BB">B</span><span style="color: #007700">\</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls function "foo" from namespace "B"<br /><br /></span><span style="color: #007700">\</span><span style="color: #0000BB">B</span><span style="color: #007700">::</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls method "foo" of class "B" from global scope<br /> // if class "B" not found, it tries to autoload class "B"<br /><br />// static methods/namespace functions of current namespace<br /><br /></span><span style="color: #0000BB">A</span><span style="color: #007700">\</span><span style="color: #0000BB">B</span><span style="color: #007700">::</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls method "foo" of class "B" from namespace "A\A"<br /> // if class "A\A\B" not found, it tries to autoload class "A\A\B"<br /><br /></span><span style="color: #007700">\</span><span style="color: #0000BB">A</span><span style="color: #007700">\</span><span style="color: #0000BB">B</span><span style="color: #007700">::</span><span style="color: #0000BB">foo</span><span style="color: #007700">(); </span><span style="color: #FF8000">// calls method "foo" of class "B" from namespace "A"<br /> // if class "A\B" not found, it tries to autoload class "A\B"<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
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