The visibility of a property or method can be defined by prefixing the
declaration with the keywords: public, protected or private. Public
declared items can be acessed everywhere. Protected limits access to
inherited classes (and to the class that defines the item). Private limits
visiblity only to the class that defines the item.
Class members must be defined with public, private, or protected.
例子 19-3. Member declaration
<?php
class MyClass {
public $public = "MyClass::public!\n";
protected $protected = "MyClass::Protected!\n";
protected $protected2 = "MyClass::Protected2!\n";
private $private = "MyClass::private!\n";
function printHello() {
print "MyClass::printHello() " . $this->private;
print "MyClass::printHello() " . $this->protected;
print "MyClass::printHello() " . $this->protected2;
}
}
class MyClass2 extends MyClass {
protected $protected = "MyClass2::protected!\n";
function printHello() {
MyClass::printHello();
print "MyClass2::printHello() " . $this->public;
print "MyClass2::printHello() " . $this->protected;
print "MyClass2::printHello() " . $this->protected2;
/* Will result in a Fatal Error: */
//print "MyClass2::printHello() " . $this->private; /* Fatal Error */
}
}
$obj = new MyClass();
print "Main:: " . $obj->public;
//print $obj->private; /* Fatal Error */
//print $obj->protected; /* Fatal Error */
//print $obj->protected2; /* Fatal Error */
$obj->printHello(); /* Should print */
$obj2 = new MyClass2();
print "Main:: " . $obj2->private; /* Undefined */
//print $obj2->protected; /* Fatal Error */
//print $obj2->protected2; /* Fatal Error */
$obj2->printHello();
?>
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注:
The use PHP 4 use of declaring a variable with the keyword 'var' is
no longer valid for PHP 5 objects. For compatiblity a variable declared
in php will be assumed with public visiblity, and a
E_STRICT warning will be issued.