language/oop5/autoload.xml
c1f37a6c270aadbbb3da56a3973ffd62197adf2b
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at the beginning of each script (one for each class).
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</para>
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<para>
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In PHP 5, this is no longer necessary. You may define an
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<function>__autoload</function> function which is automatically
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called in case you are trying to use a class/interface which hasn't been
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defined yet. By calling this function the scripting engine is given
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a last chance to load the class before PHP fails with an error.
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The <function>spl_autoload_register</function> function registers any number of
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autoloaders, enabling for classes and interfaces to be automatically loaded
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if they are currently not defined. By registering autoloaders, PHP is given
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a last chance to load the class or interface before it fails with an error.
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</para>
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<tip>
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<para>
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<function>spl_autoload_register</function> provides a more flexible
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alternative for autoloading classes. For this reason, using
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<function>__autoload</function> is discouraged and may be deprecated or
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removed in the future.
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</para>
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</tip>
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<note>
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<para>
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Prior to 5.3.0, exceptions thrown in the __autoload function could not be
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caught in the <link linkend="language.exceptions">catch</link> block and
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would result in a fatal error. From 5.3.0+ exceptions thrown in the
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__autoload function can be caught in the <link linkend="language.exceptions">
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catch</link> block, with 1 provision. If throwing a custom exception, then
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the custom exception class must be available. The __autoload function may
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be used recursively to autoload the custom exception class.
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</para>
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</note>
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<note>
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<para>
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Any class-like construct may be autoloaded the same way. That includes classes,
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interfaces, traits, and enumerations.
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</para>
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<caution>
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<para>
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Autoloading is not available if using PHP in CLI
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<link linkend="features.commandline">interactive mode</link>.
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Prior to PHP 8.0.0, it was possible to use <function>__autoload</function>
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to autoload classes and interfaces. However, it is a less flexible
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alternative to <function>spl_autoload_register</function> and
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<function>__autoload</function> is deprecated as of PHP 7.2.0, and removed
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as of PHP 8.0.0.
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</para>
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</note>
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</caution>
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<note>
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<para>
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If the class name is used e.g. in <function>call_user_func</function> then
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it can contain some dangerous characters such as <literal>../</literal>.
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It is recommended to not use the user-input in such functions or at least
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verify the input in <function>__autoload</function>.
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<function>spl_autoload_register</function> may be called multiple times in order
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to register multiple autoloaders. Throwing an exception from an autoload function,
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however, will interrupt that process and not allow further autoload functions to
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run. For that reason, throwing exceptions from an autoload function is strongly
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discouraged.
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</para>
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</note>
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<para>
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and <literal>MyClass2</literal> from the files <filename>MyClass1.php</filename>
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and <filename>MyClass2.php</filename> respectively.
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</para>
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<programlisting role="php">
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<programlisting role="php" annotations="interactive">
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<![CDATA[
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<?php
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function __autoload($class_name) {
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spl_autoload_register(function ($class_name) {
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include $class_name . '.php';
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}
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});
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$obj = new MyClass1();
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$obj2 = new MyClass2();
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<![CDATA[
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<?php
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function __autoload($name) {
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spl_autoload_register(function ($name) {
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var_dump($name);
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}
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});
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class Foo implements ITest {
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}
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@@ -95,64 +83,24 @@ Fatal error: Interface 'ITest' not found in ...
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</programlisting>
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</example>
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<example>
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<title>Autoloading with exception handling for 5.3.0+</title>
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<para>
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This example throws an exception and demonstrates the try/catch block.
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</para>
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<programlisting role="php">
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<title>Using Composer's autoloader</title>
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<simpara>
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&link.composer; generates a <literal>vendor/autoload.php</literal>
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which is set up to automatically load packages that are being managed
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by Composer. By including this file, those packages can be used without
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any additional work.
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</simpara>
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<programlisting role="php" annotations="interactive">
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<![CDATA[
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<?php
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function __autoload($name) {
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echo "Want to load $name.\n";
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throw new Exception("Unable to load $name.");
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}
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require __DIR__ . '/vendor/autoload.php';
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try {
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$obj = new NonLoadableClass();
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} catch (Exception $e) {
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echo $e->getMessage(), "\n";
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}
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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Want to load NonLoadableClass.
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Unable to load NonLoadableClass.
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]]>
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</screen>
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</example>
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<example>
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<title>Autoloading with exception handling for 5.3.0+ - Missing custom exception</title>
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<para>
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This example throws an exception for a non-loadable, custom exception.
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</para>
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<programlisting role="php">
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<![CDATA[
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<?php
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function __autoload($name) {
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echo "Want to load $name.\n";
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throw new MissingException("Unable to load $name.");
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}
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$uuid = Ramsey\Uuid\Uuid::uuid7();
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try {
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$obj = new NonLoadableClass();
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} catch (Exception $e) {
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echo $e->getMessage(), "\n";
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}
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echo "Generated new UUID -> ", $uuid->toString(), "\n";
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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Want to load NonLoadableClass.
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Want to load MissingException.
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Fatal error: Class 'MissingException' not found in testMissingException.php on line 4
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]]>
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</screen>
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</example>
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</para>
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<para>
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<simplelist>
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<member><function>unserialize</function></member>
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<member><link linkend="unserialize-callback-func">unserialize_callback_func</link></member>
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<member><function>spl_autoload</function></member>
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<member><link linkend="ini.unserialize-callback-func">unserialize_callback_func</link></member>
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<member><link linkend="ini.unserialize-max-depth">unserialize_max_depth</link></member>
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<member><function>spl_autoload_register</function></member>
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<member><function>spl_autoload</function></member>
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<member><function>__autoload</function></member>
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</simplelist>
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</para>
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</simplesect>
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Translation status