Traits vs. Interfaces

Question

I've been trying to study up on PHP lately, and I find myself getting hung up on traits. I understand the concept of horizontal code reuse and not wanting to necessarily inherit from an abstract class. What I don't understand is what is the crucial difference between using traits versus interfaces?

I've tried searching for a decent blog post or article explaining when to use one or the other, but the examples I've found so far seem so similar as to be identical.

Could anyone out there share their opinion/view on this?

Answer 1

I think traits are useful to create classes that contain methods which can be used as methods of several different classes.

For example:

trait ToolKit
{
    public $errors = array();

    public function error($msg)
    {
        $this->errors[] = $msg;
        return false;
    }
}

You can have and use this "error" method in any class that uses this trait.

class Something
{
    use Toolkit;

    public function do_something($zipcode)
    {
        if (preg_match('/^[0-9]{5}$/', $zipcode) !== 1)
            return $this->error('Invalid zipcode.');

        // do something here
    }
}

While with interfaces you can only declare the method signature, but not its functions' code. Also, to use an interface you need to follow a hierarchy, using implements. This is not the case with traits.

It is completely different!

Answer 2

An interface defines a set of methods that the implementing class must implement.

When a trait is use'd the implementations of the methods come along too--which doesn't happen in an Interface.

That is the biggest difference.

From the Horizontal Reuse for PHP RFC:

Traits is a mechanism for code reuse in single inheritance languages such as PHP. A Trait is intended to reduce some limitations of single inheritance by enabling a developer to reuse sets of methods freely in several independent classes living in different class hierarchies.

Answer 3

Traits are simply for code reuse.

Interface just provides the signature of the functions that is to be defined in the class where it can be used depending on the programmer's discretion. Thus giving us a prototype for a group of classes.

For reference- http://www.php.net/manual/en/language.oop5.traits.php

Answer 4

The trait is same as a class we can use for multiple inheritance purposes and also code reusability.

We can use trait inside the class and also we can use multiple traits in the same class with 'use keyword'.

The interface is using for code reusability same as a trait

the interface is extend multiple interfaces so we can solve the multiple inheritance problems but when we implement the interface then we should create all the methods inside the class. For more info click below link:

http://php.net/manual/en/language.oop5.traits.php http://php.net/manual/en/language.oop5.interfaces.php

Answer 5

For beginners above answer might be difficult, This is the easiest way to understand it:

Traits

trait SayWorld {
    public function sayHello() {
        echo 'World!';
    }
}

so if you want to have sayHello function in other classes without re-creating the whole function you can use traits,

class MyClass{
  use SayWorld;

}

$o = new MyClass();
$o->sayHello();

Cool right!

Not only functions you can use anything in the trait(function,variables,const..). also you can use multiple traits:use SayWorld,AnotherTraits;

Interface

  interface SayWorld {
     public function sayHello();
  }

  class MyClass implements SayWorld { 
     public function sayHello() {
        echo 'World!';
     }
}

so this is how interface different from traits: You have to re-create everything in the interface in implemented class. interface doesn't have implementation. and interface can only have functions and const, it cannot have variables.

I hope this helps!

Answer 6

An interface is a contract that says “this object is able to do this thing”, whereas a Trait is giving the object the ability to do the thing.

A Trait is essentially a way to “copy and paste” code between classes.

try reading this article