[prev in list] [next in list] [prev in thread] [next in thread] 

List:       php-doc-cvs
Subject:    [DOC-CVS] =?utf-8?q?svn:_/phpdoc/en/trunk/language/oop5/_properties.xml_variance.xml?=
From:       Peter_Cowburn <salathe () php ! net>
Date:       2019-12-17 20:24:03
Message-ID: svn-salathe-1576614243-348562-863794136 () svn ! php ! net
[Download RAW message or body]

salathe                                  Tue, 17 Dec 2019 20:24:03 +0000

Revision: http://svn.php.net/viewvc?view=revision&revision=348562

Log:
k

Changed paths:
    U   phpdoc/en/trunk/language/oop5/properties.xml
    U   phpdoc/en/trunk/language/oop5/variance.xml

Modified: phpdoc/en/trunk/language/oop5/properties.xml
===================================================================
--- phpdoc/en/trunk/language/oop5/properties.xml	2019-12-17 17:49:30 UTC (rev 348561)
+++ phpdoc/en/trunk/language/oop5/properties.xml	2019-12-17 20:24:03 UTC (rev 348562)
@@ -9,11 +9,11 @@
    "fields", but for the purposes of this reference we will use
    "properties". They are defined by using one of the
    keywords <literal>public</literal>, <literal>protected</literal>,
-   or <literal>private</literal>, followed by a normal variable
-   declaration. This declaration may include an initialization, but
-   this initialization must be a constant value--that is, it must be
-   able to be evaluated at compile time and must not depend on
-   run-time information in order to be evaluated.
+   or <literal>private</literal>, optionally followed by a type declaration,
+   followed by a normal variable declaration. This declaration may
+   include an initialization, but this initialization must be a constant
+   value--that is, it must be able to be evaluated at compile time and
+   must not depend on run-time information in order to be evaluated.
   </para>
   <para>
    See <xref linkend="language.oop5.visibility" /> for more
@@ -131,6 +131,46 @@
     Nowdoc and Heredoc support was added in PHP 5.3.0.
    </para>
   </note>
+
+  <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">
+<![CDATA[
+<?php
+
+class User
+{
+    public int $id;
+    public 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;
+
+?>
+]]>
+    </programlisting>
+    &example.outputs;
+    <screen>
+<![CDATA[
+ID: 1234
+Name: php
+]]>
+    </screen>
+   </example>
+  </para>
+
  </sect1>

 <!-- Keep this comment at the end of the file

Modified: phpdoc/en/trunk/language/oop5/variance.xml
===================================================================
--- phpdoc/en/trunk/language/oop5/variance.xml	2019-12-17 17:49:30 UTC (rev 348561)
+++ phpdoc/en/trunk/language/oop5/variance.xml	2019-12-17 20:24:03 UTC (rev 348562)
@@ -4,9 +4,16 @@
  <title>Covariance and Contravariance</title>

  <para>
+  Prior to PHP 7.4.0, class methods support mainly invariant parameter types and invariant return types.
+  This means that if a method within a parent class has a parameter type or return
+  type of <varname>T</varname>, any child method with corresponding parameter type
+  or return type <emphasis>must also</emphasis> be type <varname>T</varname>.
+ </para>
+
+ <para>
   As of PHP 7.4.0, covariance and contravariance is supported. While these concepts
-  may <emphasis>sound</emphasis> confusing, in practice they're rather simple, and extremely useful to
-  object-oriented programming.
+  may <emphasis>sound</emphasis> confusing, in practice they're rather simple, and
+  extremely useful to object-oriented programming.
  </para>

  <sect2 xml:id="language.oop5.variance.covariance">
@@ -59,10 +66,10 @@
   </informalexample>

   <para>
-   You'll notice there aren't any methods which return values in this example. We will
+   Note that there aren't any methods which return values in this example. We will
    build upon these classes with a few factories which return a new object of class type
-   <varname>Animal</varname>, <varname>Cat</varname>, or <varname>Dog</varname>. This is
-   where we can see covariance in action!
+   <varname>Animal</varname>, <varname>Cat</varname>, or <varname>Dog</varname>.
+   Covariance will come into play in the next example.
   </para>

   <informalexample>
@@ -148,8 +155,7 @@
   </informalexample>

   <para>
-   Typically, cats are picky eaters. They will eat a specific type of food, and that's it.
-   Dogs, on the other hand, will eat just about anything. Thus, we're going to override the
+   In order to see the behavior of contravariance, we will override the
    <varname>eat</varname> method in the <varname>Dog</varname> class to allow any
    <varname>Food</varname> type object. The <varname>Cat</varname> class remains unchanged.
   </para>



-- 
PHP Documentation Commits Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php

[prev in list] [next in list] [prev in thread] [next in thread]