array_filter如何返回一个对象

Question

I was following a tutorial and came across this,let's say I'm having an array of posts(objects) having two properties:

title of the post and the status (is it published or not).
and in my code I want to return those posts who are not published yet. I know there are various ways to do that but in the tutorial the code shown was like this

$posts = [
    new Post("My First Post",false),
    new Post("My Second Post",true),
    new Post("My Third Post",false),
    new Post("My Fourth Post",false),
    new Post("My Fifth Post",true),
    ];


$unpulishedPost = array_filter( $posts,function ($post){
    return !$post->published;
});

I can't get my head around how does return actually returns the entire post object when it should only returns an array of booleans shouldn't the code be like so

$unpulishedPost = array_filter( $posts,function ($post){
     if(!$post->published) 
     return $post;
});

Answer 1

class Post {
    public $title;
    public $isPublished;

    public function __construct($title, $isPublished) {
        $this->title = $title;
        $this->isPublished = $isPublished;
    }
}

$posts = [
    new Post("My First Post", false),
    new Post("My Second Post", true),
    new Post("My Third Post", false),
    new Post("My Fourth Post", false),
    new Post("My Fifth Post", true),
    ];


$unpublishedPosts = array_filter($posts, function($post) {
    return !$post->isPublished;
});

var_dump($unpublishedPosts);

This filter will return only the unpublished posts.

array(3) {
    [0] =>
    class Post#1 (2) {
      public $title =>
      string(13) "My First Post"
      public $isPublished =>
      bool(false)
    }
    [2] =>
    class Post#3 (2) {
      public $title =>
      string(13) "My Third Post"
      public $isPublished =>
      bool(false)
    }
    [3] =>
    class Post#4 (2) {
      public $title =>
      string(14) "My Fourth Post"
      public $isPublished =>
      bool(false)
    }
  }

Array_filter returns the argument of the filter callback, if the return value is true. Else it won't be pushed into the resulting array. In that way you can apply your own rules.