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what is signature of behaviors in yii? should this be a function or a class method?
Can any provide sample code?
There is no signature for behaviors, as behaviors are intented to add some function to class. Only requirement is to extend from CBehavior. Like in wiki or docs:
class SomeClass extends CBehavior
{
public function add($x, $y) { return $x + $y; }
}
class Test extends CComponent
{
public $blah;
}
$test = new Test();
// Attach behavior
$test->attachbehavior('blah', new SomeClass);
// Now you can call `add` on class Test
$test->add(2, 5);
However since PHP 5.4 you can use Traits which are native php implementation and have a lot more features, example above with traits:
// NOTE: No need to extend from any base class
trait SomeClass
{
public function add($x, $y) { return $x + $y; }
}
class Test extends CComponent
{
// Will additionally use methods and properties from SomeClass
use SomeClass;
public $blah;
}
$test = new Test();
// You can call `add` on class Test because of `use SomeClass;`
$test->add(2, 5);
There are a lot more features with traits
Related
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During some workaround with some architecture I faced a question and I am wondering if this implementation follows best practice or not.
Here we have a base abstract class:
abstract class A {
protected mixed $object;
public function __construct() {
$this->loadObject()
->fuc1();
}
abstract protected function loadObject(): self;
abstract public function fuc1(): bool;
abstract public function fuc3(): iterable;
}
In this case, I want to implement Class B and C. if I create each class separately everything is fine but as far as these 2 classes have the same functions I decided to create a base class for them (BC) so codes are now like this:
class BC extends A {
protected string x;
protected string y;
protected function loadObject(): self {
throw new \Exception('Child must implement loeadObject');
}
public function fuc1(): bool {
//Some Codes
}
public function fuc3(): iterable {
//Some Codes
}
}
And Class B and Class C are like this:
class B extends BC {
protected function loadObject(): self {
$this->object = new SomeObject();
return $this;
}
}
class C extends BC {
protected function loadObject(): self {
$this->object = new SomeObject2();
return $this;
}
}
We also can not move loadObject function to class BC cuz maybe class D wants to inherit directly from class A.
We can also rely on interfaces but I was wondering if some one forget to make class B/C implement an Interface then we will have problem in class A.
So is it a good practice that we throw exceptions in the class BC and force other developers to don't forget to overwrite the loadObject function?
This is not a good practice, if you doesn't need to implement the loadObject method in the BC class, you should keep it abstract.
abstract class BC extends A {
protected string $x;
protected string $y;
public function fuc1(): bool {
}
public function fuc3(): iterable {
}
}
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In file A,
Class A {
__construct() {
...
lots of code
...
}
public function P() {
code here
}
}
New A();
In file B,
Class B {
__construct() {
...
lots of code
...
}
public function E() {
I need to call function P in Class A
}
}
New B();
I would like to call the function P() in function E().
Is there any way to call a function in another class?
I found several ways such as dependency injection using __construct( A $aobj ) or "extends"
However, the class A was already instantiated in file A and there're a lot of things in __counstruct so I would like to know
1) the way of refractory technique
2) fancy way to call function E() in function P().
It really depends on how class B is related to A :
no link : the function in A should be static (it doesn't interact with a specific instance of A and its properties), and you can call A::P()
the class B is a child of A :
In B class definition, you have a class B extends A and in the constructor of B, you will have a parent::__construct() to call the constructor of A.
Then you can simply call $this->P() : as B is a subclass of A, and P is public (or protected), B inherits of all methods from A
The class B uses a object of type A`
Then, you must have a $a attribute in the class B, and a $this->a = new A(); in the constructor of B. You can call P with $this->a->P();
Or if you need only temporarily A in E(), you can construct a new object $a = new A(); and call $a->P(); in the code of E
Let's say that we have file a.php which contains class A:
class A {
public function __construct()
{
}
public function P()
{
echo "It is function P";
}
}
And file b.php which contains class B, in file b.php we first include a.php
include('a.php');
class B {
private $aobj;
public function __construct(){
$this->aobj = new A();
}
public function E(){
$this->aobj->P();
}
}
$b = new B();
$b->E();
Now open the browser and http://localhost/your-project/b.php and see the result.
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So, I have this class that gets used over and over again throughout my app. This is just an example, not what's actually needed to be done:
File A:
class Names {
public function first() {
echo 'Bob';
}
}
That file is autoloaded into my app using spl_autoload_register and used all throughout in other pages/classes:
File B:
class LastNames {
public function __construct() {
$this->first = new Names();
}
public function last() {
echo $this->first->first().' Smith';
}
}
$names = new LastNames();
echo $names->last(); // Bob Smith
I have many files that instantiate the class Names inside the constructor.
Does this cause much of a hit on performance?
Should I be using static function instead of public function?
Is there a better way to reuse the functions inside Names over and over again inside different classes?
You have several options, using static function is one of them :
class LastNames {
public static function foo(){
// do stuff
}
}
Or you can use a singleton :
class LastNames {
private static $instance = null;
private function __construct(){
// do stuff
}
public function foo(){
// do stuff
}
public static function getInstance(){
if ( !self::$instance ){
self::$instance = new LastNames();
}
return self::$instance;
}
}
And then you can call it with :
$lastnames = LastNames::getInstance();
$lastnames->foo();
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I have the following code in place.
Interface Vehicle which has a method calculateDistance.
Class Car implements Vehicle
Class Bicycle implements Vehicle
Class MotorCycle implements Vehicle
What I want to do next is a method in my controller that calls every class that implements Vehicle and get the values from calculateDistance.
What would be the best way/design pattern to achieve this?
At this moment I am just calling all the classes that implement the interface Vehicle (via ReflectionClass) and loop over them to call this method.
The best way is to implement CompilerPass. Here is an example .
So, create a registry class (TransportChain class in that example), interface, and all classes that implements that interface, define them as services and give them tag name.
After that, you can call that registry service in your action, and call your desired method by each service.
Basic example:
interface
interface SomeInterface {
public function doSomething();
}
Service 1:
class First implement SomeInterface {
public function doSomething() {
// do smth
}
}
Service 2:
class Second implement SomeInterface {
public function doSomething() {
// do smth
}
}
Registry class:
class MyRegistry
{
private $services = [];
public function addMyService($service)
{
$this->services[] = $service;
}
public function all()
{
return $this->services;
}
}
CompilerPass:
...
$myServices = $container->findTaggedServiceIds('my_tag');
if (empty($myServices)) {
return;
}
$registry = $container->getDefinition('my_registry');
foreach ($myServices as $key => $myService) {
$registry->addMethodCall('add', [new Reference($key)]);
}
...
After clearign the cache, you can call them in your action:
...
foreach ($this->get('my_registry')->all() as $myService) {
$myService->doSomething();
}
...
The whole other stuff, like declaring services, give them tag name, registering your compiler pass has been written here.
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Why is the following code returning NULL? I am trying to get the parent method to return a value of a property inside the parent class but for some reason it is returning null.
class A {
public $greeting;
public function __construct($message){
$this->greeting = $message;
}
public function getGreeting(){
print 1;
return $this->greeting;
}
}
class B extends A{
public function __construct(){
}
public function getGreetingMessage(){
parent::getGreeting();
}
}
$classA = new A('Hello world');
$classB = new B();
var_dump($classB->getGreetingMessage());
In the parent method "1" is being printed so I know the method is being called
Because the greeting message is not set in class b. so greeting message returns null.
1) return parent::getGreeting();
2) $classA and $classB are different instances. Whatever you set in $classA is not accessible in $classB
3) constuctor of the parent is not called from classB and, moreover, you do not provide any arguments in initialization of classB (look at 2) above)
class A {
public $greeting;
public function __construct($message){
$this->greeting = $message;
}
public function getGreeting(){
print 1;
return $this->greeting;
}
}
class B extends A{
public function __construct($message){
parent::__construct($message);
// or $this->greeting = $message;
}
public function getGreetingMessage(){
return parent::getGreeting();
}
}
$classA = new A('Hello world');
$classB = new B('Hello world 2');
var_dump($classB->getGreetingMessage());
You have to call the parent's constructor in the child class, otherwise the parent constructor is not run and the class isn't properly initialized:
class B extends A{
public function __construct($message){
parent::__construct($message);
}
So you most likely want this
$classB=new B('Hello World');