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Modernise autoloading page

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@338442 c90b9560-bf6c-de11-be94-00142212c4b1
This commit is contained in:
Thomas Punt 2016-01-08 17:38:43 +00:00
parent 1469538987
commit dcf481b64f
1 changed files with 28 additions and 25 deletions
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53
language/oop5/autoload.xml
View file

@ -9,29 +9,32 @@
at the beginning of each script (one for each class).
</para>
<para>
In PHP 5, this is no longer necessary. You may define an
<function>__autoload</function> function which is automatically
called in case you are trying to use a class/interface which hasn't been
defined yet. By calling this function the scripting engine is given
a last chance to load the class before PHP fails with an error.
In PHP 5, this is no longer necessary. The
<function>spl_autoload_register</function> function registers any number of
autloaders, enabling for classes and interfaces to be automatically loaded
if they are currently not defined. By registering autoloaders, PHP is given
a last chance to load the class or interface before it fails with an error.
</para>
<tip>
<para>
<function>spl_autoload_register</function> provides a more flexible
alternative for autoloading classes. For this reason, using
<function>__autoload</function> is discouraged and may be deprecated or
removed in the future.
Whilst the <function>__autoload</function> function can also be used for
autoloading classes and interfaces, its preferred to use the
<function>spl_autoload_register</function> function. This is because it is
a more flexible alternative (enabling for any number of autoloaders to be
specified in the application, such as in third party libraries). For this
reason, using <function>__autoload</function> is discouraged and it may be
deprecated in the future.
</para>
</tip>
<note>
<para>
Prior to 5.3.0, exceptions thrown in the __autoload function could not be
caught in the <link linkend="language.exceptions">catch</link> block and
would result in a fatal error. From 5.3.0+ exceptions thrown in the
__autoload function can be caught in the <link linkend="language.exceptions">
catch</link> block, with 1 provision. If throwing a custom exception, then
the custom exception class must be available. The __autoload function may
be used recursively to autoload the custom exception class.
Prior to PHP 5.3, exceptions thrown in the <function>__autoload</function>
function could not be caught in the
<link linkend="language.exceptions">catch</link> block and would result in
a fatal error. From PHP 5.3 and upwards, this is possible provided that if
a custom exception is thrown, then the custom exception class is available.
The <function>__autoload</function> function may be used recursively to
autoload the custom exception class.
</para>
</note>
<note>
@ -59,9 +62,9 @@
<programlisting role="php">
<![CDATA[
<?php
function __autoload($class_name) {
spl_autoload_register(function ($class_name) {
include $class_name . '.php';
}
});
$obj = new MyClass1();
$obj2 = new MyClass2();
@ -78,9 +81,9 @@ $obj2 = new MyClass2();
<![CDATA[
<?php
function __autoload($name) {
spl_autoload_register(function ($name) {
var_dump($name);
}
});
class Foo implements ITest {
}
@ -102,10 +105,10 @@ Fatal error: Interface 'ITest' not found in ...
<programlisting role="php">
<![CDATA[
<?php
function __autoload($name) {
spl_autoload_register(function ($name) {
echo "Want to load $name.\n";
throw new Exception("Unable to load $name.");
}
});
try {
$obj = new NonLoadableClass();
@ -131,10 +134,10 @@ Unable to load NonLoadableClass.
<programlisting role="php">
<![CDATA[
<?php
function __autoload($name) {
spl_autoload_register(function ($name) {
echo "Want to load $name.\n";
throw new MissingException("Unable to load $name.");
}
});
try {
$obj = new NonLoadableClass();
@ -163,7 +166,7 @@ Fatal error: Class 'MissingException' not found in testMissingException.php on l
<member><function>unserialize</function></member>
<member><link linkend="unserialize-callback-func">unserialize_callback_func</link></member>
<member><function>spl_autoload</function></member>
<member><function>spl_autoload_register</function></member>
<member><function>__autoload</function></member>
</simplelist>
</para>
</simplesect>