axiac@web

Public Properties Are Not OOP

Encapsulation is one fundamental concept of object-oriented programming. It refers to the bundling of data with the methods that operate on that data. Encapsulation is used to hide the values or state of a structured data object inside a class, preventing unauthorized parties’ direct access to them.

That’s it, the object properties (and some of its methods) should be private (or, sometimes, protected) and not public.

Let’s see an example:

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class User {
    public $name;
    public $age;
}

$user = new User();
$user->name = "John Doe";
$user->age  = 45;

printf("Name: %s, age: %d\n", $user->name, $user->age);

The code above uses the keyword “class” and because of that, according to many developers, it is object-oriented code. In fact, it is pure procedural code.

Let’s put it side-by-side against the same code written in C, a procedural language that does not provide any object-oriented feature.

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/* "Object-oriented" PHP code */          |      /* Procedural C code */
                                          |
                                          |      #include <stdlib.h>
                                          |      #include <stdio.h>
                                          |
class User {                              |      typedef struct {
    public $name;                         |          char *name;
    public $age;                          |          int age;
}                                         |      } User;
                                          |
                                          |      int main()
                                          |      {
$user = new User();                       |          User *user = malloc(sizeof(User));
$user->name = "John Doe";                 |          user->name = "John Doe";
$user->age  = 45;                         |          user->age  = 45;
                                          |
printf("Name: %s, age: %d\n",             |          printf("Name: %s, age: %d\n",
               $user->name, $user->age);  |                         user->name, user->age);
                                          |
                                          |          return 0;
                                          |      }

Letting apart the inherent differences due to syntax, can you spot any difference of style in the two fragments above? I cannot.

It is the same code, procedural beyond a shadow of a doubt.
Case closed.

Addendum: There are cases when public properties are the way to go. I’ll write about them in a future post.

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