I have seen in Laravel calling multiple method in the single line, example:
DB::get('test')->toJson();
I have a cool class and view method in that class.
$this->call->view('welcome')->anotherMethod();
I would like to call another method also? Where should I make that method?
DB::get() seems to be a method returning an object, where you can call other functions (I think a result object of a database query). If you want to call multiple functions on one object in one line, you have to return $this in your functions, e.g.:
class View {
public static function factory {
// The question is: How useful is this factory function. In fact: useless in
// the current state, but it can be extended in any way
return new self;
}
public function one() {
// do something
return $this;
}
public function two() {
// do something
return $this;
}
}
Then you can do:
$class = new View();
$class->one()->two();
// it's also possible to use the `factory` function
// you should think about, how useful this approach is in your application
$class = View::factory()->one()->two();
That's how you can do it in php, if laravel has some helpers for that, i can't say :)
Related
This is an odd situation and I think the answer is 'you can't do that, what are you thinking?' but hope someone can prove me wrong.
My goal is to store a globally scoped function in a variable then inject it for execution within a class object.
I would like to avoid using call_user_func() as this searches for the function in the global namespace and is the same effect as if I were to just execute the global function from within the class object. I would like my class to execute the object as if it were an internal class method, not an external function. This comes close but not quite.
I cannot modify the function or wrap it in a class.
(Why am I jumping through these hoops?) Needs to be used within this class to follow a spec.
I know I can just duplicate the function in the class and be done with it, but you know the issues with that (plus it creeps up on SRP.) Reflection would work perfectly but this function is not in a class, it is just out there in an include. I've tried wrapping it an anonymous function and the closure object doesn't execute the function.
Is there any hope to do this? The function is simple, accepts a scalar param, does some stuff to it, returns a value (and is tightly coupled with other code, cannot be moved or changed.)
function someFunction($param)
{
// do some stuff
return $someScalarValue;
}
What I would hope is something like
$func = someFunction([some value]); // doesn't work of course, this would store result in $func
$cls = new SomeClass($func);
Then a method in the class could run the function object, much like call_user_func but not have to search the global namespace.
protected function someThing()
{
$this->injected_function([some class value]); // also doesn't work of course
}
When you use $this you are in the objects instance scope. You could pass a (reference) method into the constructor.
$myFunc = function($arg) { var_dump($arg); return 314; };
class myClass {
private $func;
public function __construct($func) {
$this->func = $func;
}
public function do($value) {
$this->func->call($this, $value);
}
}
$var = 'Hello world!';
$myObj = new myClass($myFunc);
$value = $myObj->do($var); // $value is now 314
If you do not want the function to be stored in global namespace you can just pass even an anonymous function like this on the fly:
$myObj = new myClass(function($arg) { var_dump($arg); return 314; });
$value = $myObj->do($var); // $value is now 314
Thank you #Markkus Zeller for your comments, as I suspected there is no way to do what I originally was tasked, to "inject" a global function as an dependency. There is, but it only really works with anonymous functions.
After a lot of stressful pushback, I convinced our managers that wrapping this in a simple class was the way to go. This,
// require_once('some-function.php');
function someFunction($param)
{
// do some stuff
return $someScalarValue;
}
. . . now becomes this. (Typed out on the fly and may contain deficiencies, concept only)
// require_once('some-function.php');
require_once('path/to/SomeFunctionClass.php');
function someFunction($param)
{
$cls = new SomeFunctionClass($param);
return $cls->execute();
}
. . . where execute() contains identical code that was in someFunction(). I can now use "SomeFunctionClass" for a DI. There is more to the story, but that is the gist, and this one change can be implemented without modifying any of the 450 or so instances that use this global function (and each of those they can be gradually ported to use the new wrapper.) It also allows me to isolate and mock the functionality for unit testing.
I want to create an instance of a class and call a method on that instance, in a single line of code.
PHP won't allow calling a method on a regular constructor:
new Foo()->set_sth(); // Outputs an error.
So I'm using, if I can call it that, a static constructor:
Foo::construct()->set_sth();
Here's my question:
Is using static constructors like that considered a good practice and if yes, how would you recommend naming the methods for these static constructors?
I've been hesitating over the following options:
Foo::construct();
Foo::create();
Foo::factory()
Foo::Foo();
constructor::Foo();
Static constructors (or "named constructors") are only beneficial to prove an intention, as #koen says.
Since 5.4 though, someting called "dereferencing" appeared, which permits you to inline class instantiation directly with a method call.
(new MyClass($arg1))->doSomething(); // works with newer versions of php
So, static constructors are only useful if you have multiple ways to instantiate your objects.
If you have only one (always the same type of arguments and number of args), there is no need for static constructors.
But if you have multiple ways of instantiations, then static constructors are very useful, as it avoids to pollute your main constructor with useless argument checking, weakening languages constraints.
Example:
<?php
class Duration
{
private $start;
private $end;
// or public depending if you still want to allow direct instantiation
private function __construct($startTimeStamp = null, $endTimestamp = null)
{
$this->start = $startTimestamp;
$this->end = $endTimestamp;
}
public static function fromDateTime(\DateTime $start, \DateTime $end)
{
return new self($start->format('U'), $end->format('U'));
}
public static function oneDayStartingToday()
{
$day = new self;
$day->start = time();
$day->end = (new \DateTimeImmutable)->modify('+1 day')->format('U');
return $day;
}
}
As you can see in oneDayStartingToday, the static method can access private fields of the instance! Crazy isn't it ? :)
For a better explanation, see http://verraes.net/2014/06/named-constructors-in-php/
The naming of any method should be with intention revealing names. I can't tell what 'Foo::factory' does. Try to build to a higher level language:
User::with100StartingPoints();
This would be the same as:
$user = new User();
$user->setPointsTo(100);
You could also easily test whether User::with100StartingPoints() is equal to this.
If you don't need a reference to the newly constructed Foo, why don't you simply make set_sth a static function (and have it create a new Foo internally if required)?
If you do need to get hold of the reference, how would you do it? return $this in set_sth? But then set_sth can be made into a factory function anyway.
The only situation I can think of is if you want to call chainable methods (like in a fluent interface) on a newly constructed instance all in one expression. Is that what you are trying to do?
Anyway, you can use a general-purpose factory function for all types of objects, e.g.
function create_new($type) {
return new $type;
}
create_new('Foo')->set_sth();
It's probably not quite a best practice, but you could use the fact that functions and classes have two different namespaces : you can have a function that have the same name as a class.
This allows one to write this kind of code, for example :
function MyClass() {
return new MyClass();
}
class MyClass {
public function __construct() {
$this->a = "plop";
}
public function test() {
echo $this->a;
}
protected $a;
}
Note that I have defined a function called MyClass, and a class with the same name.
Then, you can write this :
MyClass()->test();
Which will work perfectly, and not get you any error -- here, you'll get the following output :
plop
Addition to Jon's answer: To allow constructor arguments use the following:
function create($type) {
$args = func_get_args();
$reflect = new ReflectionClass(array_shift($args));
return $reflect->newInstanceArgs($args);
}
create('Foo', 'some', 'args')->bar();
Documentation: ReflectionClass->newInstanceArgs
These are called creation methods, and I typically name them createXXX() such as createById() or createEmptyCatalog(). Not only do they provide a nice way to reveal the different intentions of an object's constructors, but they enable immediate method chaining in a fluent interface.
echo Html_Img::createStatic('/images/missing-image.jpg')
->setSize(60, 90)
->setTitle('No image for this article')
->setClass('article-thumbnail');
Propel uses a static method "create". I'd go with that. This method makes the code easier to test rather than just using static methods to perform business logic.
<?php
class MyClass
{
public static function create()
{
return new MyClass();
}
public function myMethod()
{
}
}
Besides, you can also pass parameters to the constructor. For instance:
<?php
class MyClass
{
public function __construct($param1, $param2)
{
//initialization using params
}
public static function create($param1, $param2)
{
return new MyClass($param1, $param2); // return new self($param1, $param2); alternative ;)
}
public function myMethod()
{
}
}
In either case, you'd be able to invoke myMethod right after the create method
<?php
MyClass::create()->myMethod();
// or
MyClass::create($param1, $param2)->myMethod();
A bit late to the party but I think this might help.
class MyClass
{
function __construct() {
// constructor initializations here
}
public static myMethod($set = null) {
// if myclass is not instantiated
if (is_null($set)) {
// return new instance
$d = new MyClass();
return $d->Up('s');
} else {
// myclass is instantiated
// my method code goes here
}
}
}
this can then be used as
$result = MyClass::myMethod();
optional parameters can be passed through either the __constructor or myMethod.
This is my first post and I hope I got the gimmicks right
Well,
I have a problem (ok, no real problem, but I wanna try out something new) with creating objects. Actually I have some orders, which contains a list of orderitems.
These orderitems are used and so spreaded in the whole application, and I need a way to create them. The main problem is, I want to be able to create these objects in many different ways.
Actually I do this in the class constructor and check if the argument which is given.
(I'm using php, so there is no overloading support from the language as you surely know :))
A simple and quick Example
class foo {
protected $_data=null;
public function __contruct($bar){
if (is_array($bar)){
$this->_data=$bar;
}
else {
$dataFromDb=getDataFromDatabase
$this->_data=$dataFromDb;
}
}
}
Anyway, if I want to create my object by giving another type of parameter, lets say a xml-document encapsulated in a string I need to put all this stuff in my constructor.
If the process for creating an object is more complicated, I eventually need to create a seperate method for each type, I want to initiate. But this method is only called when this special type is created. (I think you got the problem :))
Another problem comes to mind, if I need more parameters in the constructor to create a concrete object, I have modify all my code, cause the contructor changed. (Ok, I can give him more and more parameters and work with default values, but that is not what I really want).
So my Question is, which pattern fits this problem to solve my creation of a concrete object. I thought about creating a factory for each way I want to create the concrete object. But I'm not sure if this is a common solution to solve such a problem.
IF its only the signature of the constructor changing i would do it like so (a la the Zend Framework universal constructor):
class foo {
// params
public function __construct($options = null)
{
if(null !== $options)
{
$this->setOptions($options);
}
}
public function setOptions(array $options){
foreach ($options as $name => $value){
$method = 'set' . $name;
if(method_exists($this, $method)
{
$this->$method($value);
}
}
return $this;
}
}
And this essntially means all your constructor parameters are array elements with named keys, and anything you want used in this array during initialization you create a setter for and then its automatically called. The down side is the lack of effective hinting in IDEs.
On the otherhand if you want to have specific constructors then i might go with a factory but still use much the same approach:
class foo {
public static function create($class, $options)
{
if(class_exists($class))
{
$obj = new $class($options);
}
}
}
Of course you could alternatively use PHP's reflection to determine how to call the constructor instead of just injecting an arbitrary array argument.
you could simply make it a factory with optional params :)
class Example_Factory
{
public static function factory($mandatoryParam, $optionalParam = null)
{
$instance = new self;
$instance->setMandatory($mandatoryParam);
if ($optionalParam !== null) {
$instance->setOptional($optionalParam);
}
return $instance;
}
public function setMandatory($in)
{
// do something....
}
public function setOptional($in)
{
// do some more...
}
}
I tried these two ways:
(new NewsForm())->getWidgetSchema();
{new NewsForm()}->getWidgetSchema();
With no luck...
PHP does not allow you to do this. Try:
function giveback($class)
{
return $class;
}
giveback(new NewsForm())->getWidgetSchema();
It is a rather weird quirk with the language.
You can't an instanciation and a method call in one instruction... But a way to "cheat" is to create a function that returns an instance of the class you're working with -- and, then, call a method on that function which returns an object :
function my_function() {
return new MyClass();
}
my_function()->myMethod();
And, in this kind of situation, there is a useful trick : names of classes and names of functions don't belong to the same namespace -- which means you can have a class and a function that have the same name : they won't conflict !
So, you can create a function which has the same name as your class, instanciates it, and returns that instance :
class MyClass {
public function myMethod() {
echo 'glop';
}
}
function MyClass() {
return new MyClass();
}
MyClass()->myMethod();
(Yeah, the name of the function is not that pretty, in this example -- but you see the point ;-) )
If it is a static method you can just do this:
NewsForm::getWidgetSchema();
A better option in my opinion would be to use a factory method:
class factory_demo {
public static function factory()
{
return new self;
}
public function getWidgetSchema()
{ }
}
then
factory_demo::factory()->getWidgetSchema()
Of course, you get all the benefits of the factory pattern as well. Unfortunately this only works if you have access to the code, and are willing to change it.
I would like to know whether there's a way to chain methods on a newly created object in PHP?
Something like:
class Foo {
public function xyz() { ... return $this; }
}
$my_foo = new Foo()->xyz();
Anyone know of a way to achieve this?
In PHP 5.4+, the parser's been modified so you can do something like this
(new Foo())->xyz();
Wrap the instantiation in parenthesis, and chain away.
Prior to PHP 5.4, when you're using the
new Classname();
syntax, you can't chain a method call off the instantiation. It's a limitation of PHP 5.3's syntax. Once an object is instantiated, you can chain away.
One method I've seen used to get around this is a static instantiation method of some kind.
class Foo
{
public function xyz()
{
echo "Called","\n";
return $this;
}
static public function instantiate()
{
return new self();
}
}
$a = Foo::instantiate()->xyz();
By wrapping the call to new in a static method, you can instantiate a class with method call, and you're then free to chain off that.
Define a global function like this:
function with($object){ return $object; }
You will then be able to call:
with(new Foo)->xyz();
In PHP 5.4 you can chain off a newly instantiated object:
http://docs.php.net/manual/en/migration54.new-features.php
For older versions of PHP, you can use Alan Storm's solution.
This answer is outdated - therefore want to correct it.
In PHP 5.4.x you can chain a method to a new-call. Let's take this class as example:
<?php class a {
public function __construct() { echo "Constructed\n"; }
public function foo() { echo "Foobar'd!\n"; }
}
Now, we can use this: $b = (new a())->foo();
And the output is:
Constructed
Foobar'd!
Further information may be found on the manual: http://www.php.net/manual/en/migration54.new-features.php
Well, this may be an old question but as with a lot of things in programming - eventually the answer changes.
Regarding PHP 5.3, no, you can't chain directly from the constructor. To expand on the accepted answer however, in order to properly accommodate for inheritance, you can do:
abstract class Foo
{
public static function create()
{
return new static;
}
}
class Bar extends Foo
{
public function chain1()
{
return $this;
}
public function chain2()
{
return $this;
}
}
$bar = Bar::create()->chain1()->chain2();
That will work just fine and will return you a new Bar() instance.
In PHP 5.4, however, you can simply do:
$bar = (new Bar)->chain1()->chain2();
Hopefully this helps someone stumbling across the question like I have!
It would be really helpful if they 'fix this' in a future release. I really appreciate the ability to chain (especially when populating collections):
I added a method to the base class of my framework called create() that can be chained off of. Should work with all descendant classes automatically.
class baseClass
{
...
public final static function create()
{
$class = new \ReflectionClass(get_called_class());
return $class->newInstance(func_get_args());
}
...
public function __call($method, $args)
{
$matches = array();
if (preg_match('/^(?:Add|Set)(?<prop>.+)/', $method, $matches) > 0)
{
// Magic chaining method
if (property_exists($this, $matches['prop']) && count($args) > 0)
{
$this->$matches['prop'] = $args[0];
return $this;
}
}
}
...
}
Class::create()->SetName('Kris')->SetAge(36);
Just for the sake of completeness (and for the fun of it...), since nobody seems to have mentioned the solution with the shortest (and least sophisticated) code.
For frequently used short-lived objects, especially when writing test cases, where you typically do lots of object creation, you may want to optimize for typing convenience (rather than purity), and sorta' combine Alan Storm's Foo::instantiate() factory method and Kenaniah's with() global function technique.
Simply make the factory method a global function with the same name as the class!. ;-o (Either add it as a convenience wrapper around the proper static Foo::instantiate() or just move it out there while nobody is looking.)
class Foo
{
public function xyz()
{
echo "Called","\n";
return $this;
}
}
function Foo()
{
return new Foo();
}
$a = Foo()->xyz();
NOTE:
I WOULDN'T DO THIS on production code. While kinda' sexy, this is an abuse on basic coding principles (like "principle of least surprise" (although this is actually rather intuitive syntax), or "don't repeat yourself", esp. if wrapping a real factory method with some parameters, which itself, BTW, is already an abuse of DRY...), plus PHP may change in he future to break code like this in funny ways.