language/oop5/decon.xml
9f351a14a749721a74df1dc6ac9533cf796a652e
9f351a14a749721a74df1dc6ac9533cf796a652e
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@@ -138,7 +138,7 @@ class Point {
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</programlisting>
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</example>
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<para>
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When a constructor argument includes a visibility modifier, PHP will interpret it as
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When a constructor argument includes a modifier, PHP will interpret it as
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both an object property and a constructor argument, and assign the argument value to
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the property. The constructor body may then be empty or may contain other statements.
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Any additional statements will be executed after the argument values have been assigned
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</para>
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<note>
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<para>
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Using a <link linkend="language.oop5.visibility">visibility modifier</link> (<literal>public</literal>,
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<literal>protected</literal> or <literal>private</literal>) is the most likely way to apply property
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promotion, but any other single modifier (such as <literal>readonly</literal>) will have the same effect.
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</para>
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</note>
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<note>
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<para>
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Object properties may not be typed <type>callable</type> due to engine ambiguity that would
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introduce. Promoted arguments, therefore, may not be typed <type>callable</type> either. Any
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other <link linkend="language.types.declarations">type declaration</link> is permitted, however.
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</note>
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<note>
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<para>
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<!-- This should be linked once attributes are documented. -->
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Attributes placed on a promoted constructor argument will be replicated to both the property
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and argument.
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As promoted properties are desugared to both a property as well as a function parameter, any
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and all naming restrictions for both properties as well as parameters apply.
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</para>
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</note>
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<note>
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<para>
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<link linkend="language.attributes">Attributes</link> placed on a
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promoted constructor argument will be replicated to both the property
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and argument. Default values on a promoted constructor argument will be replicated only to the argument and not the property.
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</para>
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</note>
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</sect3>
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<sect3 xml:id="language.oop5.decon.constructor.new">
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<title>New in initializers</title>
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<para>
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As of PHP 8.1.0, objects can be used as default parameter values,
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static variables, and global constants, as well as in attribute arguments.
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Objects can also be passed to <function>define</function> now.
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</para>
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<note>
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<para>
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The use of a dynamic or non-string class name or an anonymous class is not allowed.
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The use of argument unpacking is not allowed.
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The use of unsupported expressions as arguments is not allowed.
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</para>
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</note>
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<example>
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<title>Using new in initializers</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// All allowed:
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static $x = new Foo;
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const C = new Foo;
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function test($param = new Foo) {}
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#[AnAttribute(new Foo)]
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class Test {
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public function __construct(
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public $prop = new Foo,
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) {}
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}
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// All not allowed (compile-time error):
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function test(
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$a = new (CLASS_NAME_CONSTANT)(), // dynamic class name
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$b = new class {}, // anonymous class
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$c = new A(...[]), // argument unpacking
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$d = new B($abc), // unsupported constant expression
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) {}
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?>
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]]>
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</programlisting>
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</example>
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</sect3>
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<sect3 xml:id="language.oop5.decon.constructor.static">
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<title>Static creation methods</title>
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<para>
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}
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public static function fromJson(string $json): static {
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$data = json_decode($json);
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$data = json_decode($json, true);
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return new static($data['id'], $data['name']);
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}
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public static function fromXml(string $xml): static {
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// Put your own logic here.
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// Custom logic here.
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$data = convert_xml_to_array($xml);
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$new = new static();
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$new->id = $data['id'];
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