Laravel calling model after declaring function with colon

Question

I was reading a short tutorial on Laravel here. Since I am not experienced in laravel or development in general I am wondering what this part of the code does exactly:

public function approve(): User

As it is seems to me, it is the same thing as just calling the model from inside the function like so:

App\User::

What is the difference in this two approches?

Answer 1

The first example you shared:

public function approve(): User

is simply a feature of PHP7 which allows you to use static type programming practices with PHP. Essentially this new function signature is telling you that this function needs to return a User type or it will throw a TypeError exception.

The second example you shared:

App\User::

is using what is called the Scope Resolution Operator(::) This operator allows you to call Class Level / Static Methods. In Laravel for example, that would be something like:

App\User::Find(1);

or

App\User::Where('id', 1);

and these differ from object level methods which would be called like so:

$user = new App\User();
$user->id = 1;
$user->save()

Notice the class instance uses the -> operator.

You can learn more about what I mentioned at the following links:

https://secure.php.net/manual/en/functions.returning-values.php#functions.returning-values.type-declaration

http://php.net/manual/en/language.oop5.paamayim-nekudotayim.php

https://laravel.com/docs/5.3/eloquent

Best of luck!

Answer 2

No, they're not the same. The first code is utilizing PHP 7's return type declerations.

It says that the method must return an instance of User class, or PHP will throw a TypeError for you. You can also specify the FQN of the class when defining return type declarations:

public function approve(): \App\User

It's specially useful when defining interfaces:

interface CommentsIterator extends Iterator {
    function current(): Comment; 
    // This enforces that any implementation of current() 
    // method, must return an instance of Comment class.
}

See what other RFCs made their way into PHP 7:
https://secure.php.net/manual/en/migration70.new-features.php

And treat yourself with Jeffrey's screencasts on PHP 7 new features:
https://laracasts.com/series/php7-up-and-running/episodes/3

But the second code (App\User::whatever()) is just calling the static method whatever() of the App\User class. It has nothing to do with the first code example which enforces return types.