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  • 位置: php7教程 -> php7语言

    php7类与对象

    PHP 5 is very very flexible in accessing member variables and member functions. These access methods maybe look unusual and unnecessary at first glance; but they are very useful sometimes; specially when you work with SimpleXML classes and objects. I have posted a similar comment in SimpleXML function reference section, but this one is more comprehensive.
    I use the following class as reference for all examples:
    <?php
    class Foo {
      public $aMemberVar = 'aMemberVar Member Variable';
      public $aFuncName = 'aMemberFunc';
      
      
      function aMemberFunc() {
        print 'Inside `aMemberFunc()`';
      }
    }
    $foo = new Foo;
    ?>
    You can access member variables in an object using another variable as name:
    <?php
    $element = 'aMemberVar';
    print $foo->$element; // prints "aMemberVar Member Variable"
    ?>
    or use functions:
    <?php
    function getVarName()
    { return 'aMemberVar'; }
    print $foo->{getVarName()}; // prints "aMemberVar Member Variable"
    ?>
    Important Note: You must surround function name with { and } or PHP would think you are calling a member function of object "foo".
    you can use a constant or literal as well:
    <?php
    define(MY_CONSTANT, 'aMemberVar');
    print $foo->{MY_CONSTANT}; // Prints "aMemberVar Member Variable"
    print $foo->{'aMemberVar'}; // Prints "aMemberVar Member Variable"
    ?>
    You can use members of other objects as well:
    <?php
    print $foo->{$otherObj->var};
    print $foo->{$otherObj->func()};
    ?>
    You can use mathods above to access member functions as well:
    <?php
    print $foo->{'aMemberFunc'}(); // Prints "Inside `aMemberFunc()`"
    print $foo->{$foo->aFuncName}(); // Prints "Inside `aMemberFunc()`"
    ?>