How to call function of just created object without temporary variable?
Code
(new \Foo())->woof();
is not valid in php.
What is right?
$obj = new Foo();
$obj->woof();
If you have got PHP 5.4 or later, you can make use of a new feature:
Class member access on instantiation has been added, e.g. (new Foo)->bar().
You can do it like this, but it's not very clean:
<?php
class Foo
{
public function __construct()
{
}
public function bar()
{
echo 'hello!';
}
}
function Foo()
{
return new Foo();
}
Foo()->bar();
You could also change it to something like
function newClass($className)
{
return new $className();
}
newClass('Foo')->bar();
But the static method way is preferred.
It can work if the object has singleton
Foo::getInstance()->woof();
BTW: it doesn't have to be even singleton but also static method which returns the instance
class Foo {
public static function & getInstance()
{
return new self();
}
}
Related
So in PHP 5.4 and up you can call a method on instantiation like so.
$class = new Foo()->methodName();
I would like to check when the class is instantiated if it was done so with a method at the same time.
Is it possible to check if the class was instantiated without a method at the same time and default to a method if not?
you can use instanceOf on the object for which you wanted to check the class.
Constructor of the class cannot return a value in php, so you can't use singleton incapsulated in constructor and have it looks nice. Of cource, you can make something like this
// NOT FOR USE
class Foo {
private static $instance;
public function __construct($skipIncapsulate = false) {
if (!$skipIncapsulation && !self::$instance)
{
self::instance = new self(true);
}
}
public function bar() {
// Do what you want with self::$instance
}
}
N.B. Do not use the example above, it is ugly solution, which also incapsulates unnecessary logic in controller, and while working with the class
Better use a usual singleton like this
class Foo {
private static $instance;
private function __construct()
{}
public static getInstance()
{
return self::$instance ?? self::$instance = new self();
}
}
Nevertheless you can create a new class FooManager, which will delegate the if the Foo class is defined
class FooManager {
private static $foo;
public function __construct()
{
self::$foo = self::$foo ?? self::$foo = new Foo();
}
public function getFoo()
{
return self::$foo;
}
}
// usage in your code
(new FooManager)->getFoo()->bar();
// You can add __call method to use (new FooManager)->foo->bar()
This will simplify working with your code. Incapsulating static self-instance in constructor is not the good practice
I'm new to programming. I have this going on:
I have Class A, which have many functions. One of those functions is functionX.
In functionX I need to make a call to functionY which belongs to another class: Class B.
So how do I acces to functionY from inside functionX?
I use Codeigniter.
Thanks in advance.
Try and experiment with this.
class ClassA {
public function functionX() {
$classB = new ClassB();
echo $classB->functionY();
}
}
class ClassB {
public function functionY() {
return "Stahp, no more OO, stahp!";
}
}
Class function? A static method?
If you have an instance (public) method, you just call $classB->functionY().
If you have a static method, you would call ClassB::functionY();
So:
class ClassA {
public function functionX(){
$classB = new ClassB();
// echo 'foo';
echo $classB->functionY();
// echo 'bar';
echo ClassB::functionYStatic();
}
}
class ClassB {
public $someVar;
public static $someVar2 = 'bar';
function __construct(){
$this->someVar = 'foo';
}
public function functionY(){
return $this->someVar;
}
public static function functionYStatic(){
return self::$someVar2;
}
}
Well that depends. If that function is a static function or not.
First off you must include the file with the class...
include_once('file_with_myclass.php');
If it is static you can call it like this:
ClassName::myFunction()
If it is not, then you create an instance of the class and then call the function on that instance.
$obj = new ClassName();
$obj->myFunction();
As you can guess the function being static means you can call it without the need of creating an instance. That is useful for example if you have a class Math and want to define a function that takes to arguments to calculate the sum of them. It wouldn't really be useful to create an instance of Math to do that, so you can declare as static and use it that way.
Here's a link to the docs with further info
http://www.php.net/manual/en/keyword.class.php
If functionY is static you can call ClassB::functionY(). Else you must create instance of Class B first. Like:
$instance = ClassB;
$instance->functionY();
But maybe you mean something else?
Looks like one of your class has a dependency to another one:
<?php
class A
{
public function x()
{
echo 'hello world';
}
}
class B
{
private $a;
public function __construct(A $a)
{
$this->a = $a;
}
public function y()
{
$this->a->x();
}
}
$a = new A();
$b = new B($a);
$b->y();
Depending how your code looks like, if it makes sense, you can inject class A into y()
public function y(A $a)
{
// your code with $a
}
If I have a class like:
class MyClass
{
public function foo()
{
echo "foo";
}
}
And then outside of the class instantiate it and try to create an anonymous function in it:
$mine = new MyClass();
$mine->bar = function() {
echo "bar";
}
And then try to call it like $mine->bar(), I get:
Fatal error: Call to undefined method MyClass::bar() in ...
How can I create an anonymous function / closure on a class instance?
Aside: Before you tell me I should rethink my logic or use interfaces and OOP properly, in my case, it's a convenience method that applies to this specific instance of a bastardized class in an attempt to clean-up a legacy procedural application. And yes, I'm using PHP 5.3+
See my blog article here: http://blog.flowl.info/2013/php-container-class-anonymous-function-lambda-support/
You need to add a magic __call function:
public function __call($func, $args) {
return call_user_func($this->$func, $args);
}
The problem is that within this construct you can call private methods from public scope.
I suggest not to simply add new variables to a class that are not defined. You can avoid this using magic __set functions and catch all undefined variables in a container (= array, like in my blog post) and change the call_user_func behaviour to call only inside the array:
// inside class:
public $members = array();
public function __call($func, $args) {
// note the difference of calling only inside members:
return call_user_func($this->members[$func], $args);
}
__call
This will work.
class Foo {
public $bar;
public function __construct()
{
$this->bar = function()
{
echo 'closure called';
};
$this->bar();
}
public function __call($method, $args) {
return call_user_func($this->$method, $args);
}
}
new Foo();
The function IS being created.
PHP has a problem with calling it.
Dirty, but works:
$f = $mine->bar;
$f();
We have the following chaining:
$obj = new obj();
$obj->setname($params1)->setcolor($params2);
Is there a way to do the same chaining on one line, without creating a dummy function?
P.S: I want to skip the part where the constructor itself is on a new line. I want to construct the object and start the chaining on the same line. Something like this:
$obj = new obj()->setname($params1)->setcolor($params2);
Since PHP 5.4, class member access on instantiation has been added so you can do it like this:
$obj = (new obj())->setname($params1)->setcolor($params2);
In previous versions, like you I hate that you have to instantiate the object on one line and then start using it on another, so I have a global function _i() which looks like this:
function _i($i) { return $i; }
I use it like this:
_i(new Obj)->doThis($param)->doThat($param2);
Some people will find it ugly but PHP lacks language expression power, so it works for me :)
I use static functions of class for it.
class a{
static public function gets($args){
return new self($args);
}
public function do_other(){
}
}
a::gets()->do_other();
Usually there are more then I static method to different usages
Should be possible if you allways return the object itself in the function.
function setname($param) {
// set the name etc..
return $this;
}
You can also use PHP type hinting to make sure only the correct object is used as an argument
function instance(sdtClass $instance) { return $instance }
or as the static method using the class name
class CustomClass{
static public function gets(CustomClass $obj){
return $obj;
}
}
You can also use this technique from Singleton pattern (without using singleton pattern):
<?php
class test
{
public function __construct() {
}
public static function getInstance() {
return new test();
}
public function chain() {
echo 'ok';
}
}
// outputs 'ok'
$test = test::getInstance()->chain();
Sure is. Simplt return this at the end of each function, to return the object so your next chained function can use it.
<?php
class A
{
public __constructor()
{ .... }
public function B($params)
{
//Processing
return this;
}
public function C($params)
{
//Processing
return this;
}
public function D($params)
{
//Processing
}
}
$O = new A();
$O->B($params)->C($params)->D($params); //Will work because B and C return this
$O->B($params)->D($params)->C($params); //WILL NOT work because D doesn't return this
?>
So i was wondering if there is a way to method chain, when the initial method is a static function. Here is what I mean:
class foo
{
public static function a()
{
$foo = new foo;
return $foo->bar();
}
public function bar()
{
return $this;
}
public function b()
{
return 1;
}
}
print foo::a()->b();
EDIT
print foo::a()->b(); not print foo:a()->b();
Static Methods or Other Methods, as long as the method is returning an object either self or some other, the methods can be chained, with the same method you are attempting.
class foo {
public function __construct() {
}
public function create() {
// create something;
return $this;
}
public function performSomethingElse() {
// perform something
return $this;
}
}
$object = new foo;
$object -> create() -> performSomethingElse();
this line
print foo:a();
should be
print foo::a();
and you will not be able to return $this in a static method
it needs to be instantiated first:
$foo = new Foo();
print $foo->a()->b();
Only sort of an answer, and somewhat idiosyncratic:
But I would advise that you have your object accompanied by a factory procedure instead:
class foo { .... }
function foo() { return new foo; }
This might remove some of the confusion for you. And it even looks a bit nicer by avoiding the mix of static and object method calls:
foo()->bar()->b();
It basically externalizes the static function. And your object only implements the chainable methods which return $this, or actual results.