add a note
For real quick and dirty one-liner anonymous objects, just cast an associative array:
<?php
$obj = (object) array('foo' => 'bar', 'property' => 'value');
echo $obj->foo; // prints 'bar'
echo $obj->property; // prints 'value'
?>
... no need to create a new class or function to accomplish it.
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()`"
?>
There are a couple of tricks you can do with PHP's classes that programmers from C++, etc., will find very peculiar, but which can be useful.
You can create instances of classes without knowing the class name in advance, when it's in a variable:
<?php
$type = 'cc';
$obj = new $type; // outputs "hi!"
class cc {
function __construct() {
echo 'hi!';
}
}
?>
You can also conditionally define them by wrapping them in if/else blocks etc, like so:
<?php
if (expr) {
class cc {
// version 1
}
} else {
class cc {
// version 2
}
}
?>
It makes up for PHP's lack of preprocessor directives. The caveat is that the if/else code body must have been executed before you can use the class, so you need to pay attention to the order of the code, and not use things before they're defined.
As of PHP 5.3, $className::funcName() works fine.
<?php
class test
{
public static function run() { print "Works\n"; }
}
$className = 'test';
$className::run();
?>
on my system, prints "Works". May work with earlier versions of PHP as well. Even if it doesn't, there's always
<?php
$className = 'test';
call_user_func(array($className, 'run'));
?>
The point is, there's no need for eval.
With regards to Singleton patterns (and variable class names) - try:
<?php
class MyClass {
// singleton instance
private static $instance;
// private constructor function
// to prevent external instantiation
private __construct() { }
// getInstance method
public static function getInstance() {
if(!self::$instance) {
self::$instance = new self();
}
return self::$instance;
}
//...
}
?>
Maybe someone will find these classes, which simulate enumeration, useful.
<?php
class Enum {
protected $self = array();
public function __construct( /*...*/ ) {
$args = func_get_args();
for( $i=0, $n=count($args); $i<$n; $i++ )
$this->add($args[$i]);
}
public function __get( /*string*/ $name = null ) {
return $this->self[$name];
}
public function add( /*string*/ $name = null, /*int*/ $enum = null ) {
if( isset($enum) )
$this->self[$name] = $enum;
else
$this->self[$name] = end($this->self) + 1;
}
}
class DefinedEnum extends Enum {
public function __construct( /*array*/ $itms ) {
foreach( $itms as $name => $enum )
$this->add($name, $enum);
}
}
class FlagsEnum extends Enum {
public function __construct( /*...*/ ) {
$args = func_get_args();
for( $i=0, $n=count($args), $f=0x1; $i<$n; $i++, $f *= 0x2 )
$this->add($args[$i], $f);
}
}
?>
Example usage:
<?php
$eFruits = new Enum("APPLE", "ORANGE", "PEACH");
echo $eFruits->APPLE . ",";
echo $eFruits->ORANGE . ",";
echo $eFruits->PEACH . "\n";
$eBeers = new DefinedEnum("GUINESS" => 25, "MIRROR_POND" => 49);
echo $eBeers->GUINESS . ",";
echo $eBeers->MIRROR_POND . "\n";
$eFlags = new FlagsEnum("HAS_ADMIN", "HAS_SUPER", "HAS_POWER", "HAS_GUEST");
echo $eFlags->HAS_ADMIN . ",";
echo $eFlags->HAS_SUPER . ",";
echo $eFlags->HAS_POWER . ",";
echo $eFlags->HAS_GUEST . "\n";
?>
Will output:
1, 2, 3
25, 49
1,2,4,8 (or 1, 10, 100, 1000 in binary)
Here a simple class 'stdObject' that give us the possibility to create dynamic classes and the possibility to add and execute methods thing that 'stdClass' don't let us do. Very useful if you extends it to a controller on MVC Design pattern. Let users create own classes.
I have also post this class on http://www.php.net/manual/en/language.types.object.php
<?php
class stdObject {
public function __construct(array $arguments = array()) {
if (!empty($arguments)) {
foreach ($arguments as $property => $argument) {
$this->{$property} = $argument;
}
}
}
public function __call($method, $arguments) {
$arguments = array_merge(array("stdObject" => $this), $arguments); // Note: method argument 0 will always referred to the main class ($this).
if (isset($this->{$method}) && is_callable($this->{$method})) {
return call_user_func_array($this->{$method}, $arguments);
} else {
throw new Exception("Fatal error: Call to undefined method stdObject::{$method}()");
}
}
}
// Usage.
$obj = new stdObject();
$obj->name = "Nick";
$obj->surname = "Doe";
$obj->age = 20;
$obj->adresse = null;
$obj->getInfo = function($stdObject) { // $stdObject referred to this object (stdObject).
echo $stdObject->name . " " . $stdObject->surname . " have " . $stdObject->age . " yrs old. And live in " . $stdObject->adresse;
};
$func = "setAge";
$obj->{$func} = function($stdObject, $age) { // $age is the first parameter passed when calling this method.
$stdObject->age = $age;
};
$obj->setAge(24); // Parameter value 24 is passing to the $age argument in method 'setAge()'.
// Create dynamic method. Here i'm generating getter and setter dynimically
// Beware: Method name are case sensitive.
foreach ($obj as $func_name => $value) {
if (!$value instanceOf Closure) {
$obj->{"set" . ucfirst($func_name)} = function($stdObject, $value) use ($func_name) { // Note: you can also use keyword 'use' to bind parent variables.
$stdObject->{$func_name} = $value;
};
$obj->{"get" . ucfirst($func_name)} = function($stdObject) use ($func_name) { // Note: you can also use keyword 'use' to bind parent variables.
return $stdObject->{$func_name};
};
}
}
$obj->setName("John");
$obj->setAdresse("Boston");
$obj->getInfo();
?>
A little trick for create an anonymous object (exactly an half-anonymous object :D aka "_") who can handle methods.
<?php
class _
{
public function __construct( array $cfg){
foreach($cfg as $k=>$v){
$this->{$k}=$v;
}
}
public function __call( $fn, array $args){
if(isset($this->{$fn})){
array_unshift($args, $this);
call_user_func_array( $this->{$fn}, $args);
}
}
}
$o = new _(array(
"color"=>"red",
"run"=>function($this){
echo "My color is : ".$this->color;
}
));
$o->run();
?>
