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A basic overview of how method-chaining works in PHP.


class QueryMaker
    $table = '';
$field = '';

    // this is a static method, it doesn't
    // run on an object, it only runs on a class
    public static function make()
        // create an instance of class
        // QueryMaker and return it
        return new static();

    // this is not static, it doesn't run on
    // a class, only on an object
    public function setTable($name)
        $this->table = $name;
        return $this;

    // this is also not static
    public function setField($name)
        $this->field = $name;
        return $this;

    // again, not static, just renders
    // the "query"
    public function flush()
        return "select {$this->field} from {$this->table}";

// Here is the implementation with method chaining
$query = QueryMaker::make()->setTable('users')->setField('name')->flush();

// Here is the implementation without method chaining
$object = new QueryMaker();
$query = $object->flush();
// the output is: select name from users

// The methods setTable() and setField() return $this.
// In that context $this is the QueryMaker object that was created by make().

// Let's go step by step:

$query = QueryMaker::make()->setTable('users')->setField('name')->flush();
// The static method QueryMaker::make() returns an object instantiation of the QueryMaker class.

$query = $object->setTable('users')->setField('name')->flush();
// $object->table is set, setTable() returns the object instance.

$query = $object->setField('name')->flush();
// $object->field is set, setField() returns the object instance.

$query = $object->flush();
// The flush method is called on the object, returning the string.