So I currently have a class and wanted to make class calls cleaner by being able to call the class instance as a function, like the __toString magic method which outputs a string when called, instead be able to call $instance() as a function and have it called.
Like:
class MyClass {
public function __onCall() {
echo 'This was called when the user called the instance!';
}
}
$instance = new MyClass();
$instance();
//opts: This was called when the user called the instance!
Essentially I want to be able to chain class functions and cut off one chain that'll be called a lot by calling a function from the instance.
Syntax I want:
$Class('Some String')->SomeFunction()->AnotherFunction();
Syntax I have:
$Class->select_string('Some String')->SomeFunction()->AnotherFunction();
:-)
Ok. I see what you mean here. So you want to have a fluent method chaining. This is actually answered by another thread
Hope this helps.
Related
Within a single class, I am able to use the _call/_callStatic functions to call a function before any function is actually run. However, I'm yet to find a solution that I can apply to the parent, and it will be inherited by the children.
The only method I can think of is putting a small snippet of code within each class that calls a function in the parent, which contains my code.
Are there any better solutions that I can implement?
As long as you are at least on php 5.4, you could use traits.
http://php.net/traits
This will need some adjustments in your code but could allow the desired behavior.
Do you have some more information on your use case? I think of logging from your description, is this correct?
Unfortunately there are not magic methods in PHP which get run whenever any method is called.
I think the solution you are looking for is a decorator, see this article for the tips on decorating methods / classes in PHP.
how to implement a decorator in PHP?
It's hard to help you without seeing some code. However, assuming that you don't re-define __call/__callStatic in the subclass, it should simply inherit the method from it's superclass.
If you do re-define __call/__callStatic in the subclass, it overrides the superclass' definition. So you'd somehow have to call the superclass' method. In order to do this you can use the parent keyword. See this example:
class SuperClass
{
public function __call($name, $arguments)
{
// Do some stuff
}
}
class SubClass extends SuperClass
{
public function __call($name, $arguments)
{
// Execute the parent's __call() method
return parent::__call($name, $arguments);
// Do some extra stuff here
}
}
I have a child class that extends a class with only static methods. I would like to make this child class a singleton rather than static because the original developer really wanted a singleton but used static instead (obvious because every method in the static class calls the Init() function (basically a constructor)).
Most of the methods in the parent don't need to be overwritten in the child, but I would like to avoid having to write methods like this:
public function Load($id)
{
return parent::Load($id);
}
when I would prefer not to overwrite the method at all and just use:
$child->Load($id);
Is it possible to call a static method non-statically? Is it possible to extend a static object with an instance object? I know I can try it and it will likely work (PHP is very forgiving), but I don't know if there is anything I should be concerned about.
Can you inherit static methods?
Yes
Can you override static methods?
Yes, but only as of PHP 5.3 do they work as you would expect: http://www.php.net/manual/en/language.oop5.static.php (ie. self binds to the actual class and not the class it's defined in).
Is it possible to call a static method non-statically?
Yes, but will lose $this. You don't get a warning (yet) but there also isn't really a reason to call it the wrong way.
Two part answer.
First, about the titular question: calling a static method non-statically is perfectly fine; #SamDark's comment is correct. It does not produce a warning, nor does it cause any kitten murdering. Try it:
<?php
class test {
public static function staticwarnings(){
echo "YOU ARE (statically) WARNED!\n";
}
}
error_reporting(E_ALL);
$test = new test();
echo "\n\ncalling static non-statically\n";
$test->staticwarnings();
If you had an instance reference, $this, in that static method, then you would get a fatal error. But that is true regardless of how you call it.
Once again, there isn't a warning, nor any kitten killed.
Second part of the answer:
Calling an overridden parent function from an overriding child class requires something called "scope resolution". What the OP is doing in their method is NOT calling a static method. (Or at least, it doesn't have to be; we can't see the parent implementation). The point is, using the parent keyword is not a static call. Using the :: operator on an explicit parent class name is also not a static call, if it is used from an extending class.
Why is that documentation link so strangely named? It's literally Hebrew. If you've ever run into an error related to it, you might have observed the delightfully-named parser error code T_PAAMAYIM_NEKUDOTAYIM.
With learning fuelPHP, I am introduced on calling classes using scope resolution, or :: in sense. Typically, when we call a method in a class we do this ...
$myclass = new myclass();
$myclass->mymethod();
On fuel, methods are usually called in this manner ...
myclass::mymethod();
I was wondering if there are any difference between the two? Is the scope resolution is something of an update on 5.3 as well ... if not, which one is ideal, or when should I use these.
Thanks.
The scope resolution operator is used to access either class constants like ::const, static variables like ::$var or call static methods like ::method().
See http://php.net/manual/en/language.oop5.static.php
Static methods can be called without having an instance of the class they are defined in. They're defined in that class with the static keyword.
For example, one of CakePHP's static methods is defined like this:
class ClassRegistry {
// ...
public static function &getInstance() {
// ...
}
}
... which you can call like ClassRegistry::getInstance().
Without the static keyword, you'd need an instance of the ClassRegistry class to call that function.
You can read more here, especially about why using static methods in your own code can sometimes be a bad idea: http://kore-nordmann.de/blog/0103_static_considered_harmful.html
I am not sure how would myclass::mymethod(); work, since I use such syntax only when I am calling a STATIC class.
MyClass::DoSomething();
would call a static method named DoSomething()
while
$instance = new MyClass();
$instance->DoSomething();
would call the instance method.
I have not tested it but I believe you will run into an error if you do $instance::DoSomething()
I think the best way to understand why there is a static call and what it does behind the scene is to check this FuelPHP blog's entry: http://fuelphp.com/blog/2011/05/why-did-you-do-that
The obvious difference is that the first solution $myObject->myMethod() it's a dynamic call : you need an instance to execute myMethod().
In the second solution, MyClass::myMethod() is a static call. The class acts as a sort of namespace where a function belong. You don't need an instance for that.
Perhaps it is a very simple issue, but I'm missing something in OOP fundamentals. Suppose I have to php file, say file1 and file2. file1 implements a class from the class Class, and in some of the method of the latter, say MethodA. In MethodA, I instantiate a class say $object from the class Object (which comes from another file3), and I call a method, say MethodB that takes as an argument the instantiation $object, and processes to set the value of one attribute of the instantiation $object. So, the scheme is the following :
class Class{
public function MethodB($object){
$param
...
$object->setValue($param);
...
}
public function MethodA(){
$object = new Object;
...
$this->MethodB($object);
...
$object->getValue();
}
}
Now the problem is that I am not able to get back the value of $object->getValue($param), and the question is why?
This is somewhat a follow up to a previous question - but I've distilled the question down and have the "works" vs. "doesn't work" cases narrowed down much more precisely.
My Goal:
I have a class MyClass that has an instance variable myFunction. Upon creating a MyClass object (instantiating), the constructor assigns the instance variable myFunction with the result of a call to create_function (where the code and args come from a db call).
Once this object of type MyClass is created (and stored as an instance variable of another class elsewhere) I want to be able to call myFunction (the instance variable anonymous function) from "anywhere" that I have the MyClass object.
Experimental Cases -- below is my highly simplified test code to illustrate what works vs. what doesn't (i.e. when the expected functionality breaks)
class MyClass extends AnotherClass {
public $myFunction;
function __construct() {
$functionCode = 'echo "NyanNyanNyan";';
$this->myFunction();
/*Now the following code works as expected if put in here for testing*/
$anonFunc = $this->myFunction;
$anonFunc(); //This call works just fine (echos to page)!
/*And if i make this call, it works too! */
self::TestCallAnon();
}
public function TestCallAnon() {
$anonFunc2 = $this->myFunction;
$anonFunc2();
}
}
However, if I do the following (in another file, it errors saying undefined function () in... within the Apache error log.
//I'm using Yii framework, and this is getting the user
//objects instance variable 'myClass'.
$object = Yii::app()->user->myClass;
$object->TestCallAnon(); // **FAILS**
or
$func = $object->myFunction;
$func(); // ** ALSO FAILS **
In addition, several variations of calls to call_user_func and call_user_func_array don't work.
If anyone is able to offer any insight or help that would be great :).
Thanks in advance!
You can't pass references to functions around in PHP like you can in for instance JavaScript.
call_user_func has limited functionality. You can use it like so:
class MyClass {
function func() {}
static function func() {}
}
function myfunc() {}
$i = new MyClass();
call_user_func("myfunc", $args);
call_user_func(array($i, "func"), $args);
call_user_func(array(MyClass, "staticFunc"), $args);
I ended up solving this issue via a workaround that ended up being a better choice anyways.
In the end I ended up having a static class that had a method to randomly return one of the possible identifiers, and then another method which accepted that identifier to build the anonymous function upon each class.
Slightly less elegant than I would like but it ends up working well.
Thanks to everyone for your efforts.