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more details for typed properties

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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@350015 c90b9560-bf6c-de11-be94-00142212c4b1
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Peter Cowburn 2020-06-08 20:49:01 +00:00
parent 520d8f432f
commit a43655118b
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244
language/oop5/properties.xml
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@ -4,10 +4,10 @@
<title>Properties</title>
<para>
Class member variables are called "properties". You may also see
them referred to using other terms such as "attributes" or
"fields", but for the purposes of this reference we will use
"properties". They are defined by using one of the
Class member variables are called <emphasis>properties</emphasis>. You may also see
them referred to using other terms such as <emphasis>attributes</emphasis> or
<emphasis>fields</emphasis>, but for the purposes of this reference we will use
<emphasis>properties</emphasis>. They are defined by using one of the
keywords <literal>public</literal>, <literal>protected</literal>,
or <literal>private</literal>, optionally followed by a type declaration,
followed by a normal variable declaration. This declaration may
@ -101,15 +101,17 @@ EOD;
</para>
</note>
<para>
As of PHP 5.3.0
<link linkend="language.types.string.syntax.heredoc">heredocs</link> and
<link linkend="language.types.string.syntax.nowdoc">nowdocs</link>
can be used in any static data context, including property
declarations.
<example>
<title>Example of using a nowdoc to initialize a property</title>
<programlisting role="php">
<sect2 xml:id="language.oop5.properties.heredoc-nowdoc">
<title>Heredoc and Nowdoc</title>
<para>
As of PHP 5.3.0
<link linkend="language.types.string.syntax.heredoc">heredocs</link> and
<link linkend="language.types.string.syntax.nowdoc">nowdocs</link>
can be used in any static data context, including property
declarations.
<example>
<title>Example of using a nowdoc to initialize a property</title>
<programlisting role="php">
<![CDATA[
<?php
class foo {
@ -123,53 +125,215 @@ EOT;
}
?>
]]>
</programlisting>
</example>
</para>
<note>
<para>
Nowdoc and Heredoc support was added in PHP 5.3.0.
</programlisting>
</example>
</para>
</note>
<note>
<para>
Nowdoc and Heredoc support was added in PHP 5.3.0.
</para>
</note>
</sect2>
<para>
As of PHP 7.4.0, property definitions can include a type declaration, with the exception of
the <literal>callable</literal> type.
<example>
<title>Example of typed properties</title>
<programlisting role="php">
<sect2 xml:id="language.oop5.properties.typed-properties">
<title>Type declarations</title>
<para>
As of PHP 7.4.0, property definitions can include a type declaration.
<example>
<title>Example of typed properties</title>
<programlisting role="php">
<![CDATA[
<?php
class User
{
public int $id;
public string $name;
public ?string $name;
public function __construct(int $id, string $name)
public function __construct(int $id, ?string $name)
{
$this->id = $id;
$this->name = $name;
}
}
$user = new User(1234, "php");
echo "ID: " . $user->id;
echo "\n";
echo "Name: " . $user->name;
$user = new User(1234, null);
var_dump($user->id);
var_dump($user->name);
?>
]]>
</programlisting>
&example.outputs;
<screen>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
ID: 1234
Name: php
int(1234)
NULL
]]>
</screen>
</example>
</para>
</screen>
</example>
</para>
<para>
Typed properties must be initialized before accessing, otherwise an
<classname>Error</classname> is thrown.
<example>
<title>Accessing properties</title>
<programlisting role="php">
<![CDATA[
<?php
class Shape
{
public int $numberOfSides;
public string $name;
public function setNumberOfSides(int $numberOfSides): void
{
$this->numberOfSides = $numberOfSides;
}
public function setName(string $name): void
{
$this->name = $name;
}
public function getNumberOfSides(): int
{
return $this->numberOfSides;
}
public function getName(): string
{
return $this->name;
}
}
$triangle = new Shape();
$triangle->setName("triangle");
$triangle->setNumberofSides(3);
var_dump($triangle->getName());
var_dump($triangle->getNumberOfSides());
$circle = new Shape();
$circle->setName("circle");
var_dump($circle->getName());
var_dump($circle->getNumberOfSides());
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
string(8) "triangle"
int(3)
string(6) "circle"
Fatal error: Uncaught Error: Typed property Shape::$numberOfSides must not be accessed before initialization
]]>
</screen>
</example>
</para>
<sect3 xml:id="language.oop5.properties.typed-properties.valid-types">
<title>Valid property types</title>
<informaltable>
<tgroup cols="3">
<thead>
<row>
<entry>Type</entry>
<entry>Description</entry>
<entry>Minimum PHP version</entry>
</row>
</thead>
<tbody>
<row>
<entry><type>bool</type></entry>
<entry>
The property must be <type>boolean</type> value.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><type>int</type></entry>
<entry>
The property must be an <type>integer</type>.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><type>float</type></entry>
<entry>
The property must be a <type>float</type>ing point number.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><type>string</type></entry>
<entry>
The property must be a <type>string</type>.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><type>array</type></entry>
<entry>
The property must be an <type>array</type>.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><literal>object</literal></entry>
<entry>
The property must be an <type>object</type>.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><literal>iterable</literal></entry>
<entry>
The property must be either an <type>array</type> or an &instanceof;
<interfacename>Traversable</interfacename>.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><literal>self</literal></entry>
<entry>
The property must be an &instanceof; the same class in which the
property is defined.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry><literal>parent</literal></entry>
<entry>
The property must be an &instanceof; the parent class of the class
in which the property is defined.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry>Class/interface name</entry>
<entry>
The property must be an &instanceof; the given class or interface
name.
</entry>
<entry>PHP 7.4.0</entry>
</row>
<row>
<entry>?type</entry>
<entry>
The property must be the specified type, or &null;.
</entry>
<entry>PHP 7.4.0</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</sect3>
</sect2>
</sect1>