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In this tutorial, we'll gonna introduce some "tools" that would allow us to check an object's parents, its class, what it has inherited and what interfaces are implemented upon it. I won't go through all of the functions because they are a lot and besides, the majority of them are really self-explanatory and the documentation about them is good enough even for beginners.
I'll be using the following files in this tutorial (stating it here to avoid confusion): index.php, SuperMan.php, Human.php.
Let's include the SuperMan.php file in our index.php
In the SuperMan.php file I have included Human.php and made a class with a few methods for data supply. Here is the code so that you may gain better understanding and of course to be able to carry on with the tutorial.
<?php
include 'Human.php';
class SuperMan extends Human{
public function __construct() {
parent::__construct();
echo 'Superman construction<br />';
}
public function goToEat(){
echo 'I refuse';
}
public function showFace(){
echo 'Show<br />';
}
public function drive(){
$this->driveCar();
}
}
?>[/code]
So index.php inherits SuperMan and SuperMan by itself inherits Human.php. Human.php has an included Animal.php class and so on. The idea is just to have multiple inherits of classes and objects so that we may show how it works. Now here is the class Human (it has nothing specific within it - just a few more methods).
Now let's make a new instance of SuperMan in our index.php and we want to check whether that object that is appended to the variable $human is an instance of the class SuperMan. So let's do this with the well-known function var_dump() and use the keyword instanceof. First we define the variable that is handling the instance then we use the keyword instanceof and the name of the class.
Within the second pair of brackets, we'll receive the output in boolean type. Since the object $human is an instance of SuperMan so therefore we get returned:
What if we want to check whether the object is from class Animal.
We will get the same result because Animal is the main class. Basically, speaking SuperMan inherits Human, Human inherits Animal. So SuperMan is part of the class Animal, so instance of will return us a boolean true for any of the classes we currently dispose with because that is the so-called tree structure. This is the way we can validate whether an outside object corresponds to the requirements we have defined. Later on you'll see that in object-oriented programming a lot of objects are being gathered in a file and let's say we have an incoming object and we would then want to validate whether the object is from the correct type and whether it implements the appropriate interfaces.
Let's run the following:
The examples I've given above are just comparing and checking class names but we can also use variables like in this example to validate the object and instance. So practically whether one object is an instance of another.
Now there are several other functions that are used in more specific cases. Some of them are:class_alias();
- Generates an alias of a desired class
class_exists();
- Checks whether the class has been defined
get_class();
- Outputs the name of a class that is part of an object
is_a();
- Checks whether an object is of a class and does not include interface implementations like instanceof
method_exists();
- Checks whether a class method is available
property_exists();
- Checks whether an object or a class has a defined property
trait_exists();
- Checks whether a trait is existent
Basically, documenting is just writing comments but in a more specific way. Most people would ignore that totally, but when it comes to massive projects, all those tiny little things I use to talk about in my tutorials and anywhere at all will come in handy for sure. As well as that, documentation is useful for other programmers that would interfere in our code or just for our own ease.
This template is generated by an IDE (Netbeans). Those types of comments are specific for object-oriented programming and luckily they are almost the same in all programming languages. It's accepted that when we have a class, the first few lines should be describing it most briefly, from which object it is, whether it is part of an administration module and so on. We don't need to be too describing, we just need to handle the idea of what the project is about. Whether it would be a GPL, Apache or open source license and so on.
Now when we have this:
In Netbeans there is a whole documentation about them in the environment itself. They are all more than self-explanatory and their usage is totally unnecessary but in order to keep things 'tidy' and help ourselves when we are releasing the code as a product, we'd require those comments and documentations at the beginning of our file, whether it would be our license, copyright, disclaimer, about section or whatever.
Now let's make a simple and pretty much the most basic method we could think of just to see it in practical use:
We'll get the documentation we had written some time ago for the method that we are referring to. The reason why I made a second method with no return value is that we could use it as an auto-completion example but we are good without it as well. So here's what our documentation is being represented like in Netbeans.
Now let's document a single property. There is again, literally, no difference. Though it is rarely used to document properties especially, I just want to put an example to make it clear that there is practically no difference and nothing confusing.
I'll be using the following files in this tutorial (stating it here to avoid confusion): index.php, SuperMan.php, Human.php.
Let's include the SuperMan.php file in our index.php
In the SuperMan.php file I have included Human.php and made a class with a few methods for data supply. Here is the code so that you may gain better understanding and of course to be able to carry on with the tutorial.
<?php
include 'Human.php';
class SuperMan extends Human{
public function __construct() {
parent::__construct();
echo 'Superman construction<br />';
}
public function goToEat(){
echo 'I refuse';
}
public function showFace(){
echo 'Show<br />';
}
public function drive(){
$this->driveCar();
}
}
?>[/code]
So index.php inherits SuperMan and SuperMan by itself inherits Human.php. Human.php has an included Animal.php class and so on. The idea is just to have multiple inherits of classes and objects so that we may show how it works. Now here is the class Human (it has nothing specific within it - just a few more methods).
Now let's make a new instance of SuperMan in our index.php and we want to check whether that object that is appended to the variable $human is an instance of the class SuperMan. So let's do this with the well-known function var_dump() and use the keyword instanceof. First we define the variable that is handling the instance then we use the keyword instanceof and the name of the class.
Within the second pair of brackets, we'll receive the output in boolean type. Since the object $human is an instance of SuperMan so therefore we get returned:
What if we want to check whether the object is from class Animal.
We will get the same result because Animal is the main class. Basically, speaking SuperMan inherits Human, Human inherits Animal. So SuperMan is part of the class Animal, so instance of will return us a boolean true for any of the classes we currently dispose with because that is the so-called tree structure. This is the way we can validate whether an outside object corresponds to the requirements we have defined. Later on you'll see that in object-oriented programming a lot of objects are being gathered in a file and let's say we have an incoming object and we would then want to validate whether the object is from the correct type and whether it implements the appropriate interfaces.
Let's run the following:
The examples I've given above are just comparing and checking class names but we can also use variables like in this example to validate the object and instance. So practically whether one object is an instance of another.
Now there are several other functions that are used in more specific cases. Some of them are:class_alias();
- Generates an alias of a desired class
class_exists();
- Checks whether the class has been defined
get_class();
- Outputs the name of a class that is part of an object
is_a();
- Checks whether an object is of a class and does not include interface implementations like instanceof
method_exists();
- Checks whether a class method is available
property_exists();
- Checks whether an object or a class has a defined property
trait_exists();
- Checks whether a trait is existent
This template is generated by an IDE (Netbeans). Those types of comments are specific for object-oriented programming and luckily they are almost the same in all programming languages. It's accepted that when we have a class, the first few lines should be describing it most briefly, from which object it is, whether it is part of an administration module and so on. We don't need to be too describing, we just need to handle the idea of what the project is about. Whether it would be a GPL, Apache or open source license and so on.
Now when we have this:
In Netbeans there is a whole documentation about them in the environment itself. They are all more than self-explanatory and their usage is totally unnecessary but in order to keep things 'tidy' and help ourselves when we are releasing the code as a product, we'd require those comments and documentations at the beginning of our file, whether it would be our license, copyright, disclaimer, about section or whatever.
We'll get the documentation we had written some time ago for the method that we are referring to. The reason why I made a second method with no return value is that we could use it as an auto-completion example but we are good without it as well. So here's what our documentation is being represented like in Netbeans.