Referencing a class or function in a namespace

namespace MyProject\Shapes;

class Rectangle { ... }

$rectangle = new MyProject\Shapes\Rectangle();

// Rectangle becomes an alias to MyProject\Shapes\Rectangle
use MyProject\Shapes\Rectangle;

$rectangle = new Rectangle();

use MyProject\Shapes\{
    Rectangle,         //Same as `use MyProject\Shapes\Rectangle`
    Circle,            //Same as `use MyProject\Shapes\Circle`
    Triangle,          //Same as `use MyProject\Shapes\Triangle`
    
    Polygon\FiveSides, //You can also import sub-namespaces
    Polygon\SixSides   //In a grouped `use`-statement
};

$rectangle = new Rectangle();

use MyProject\Shapes\Oval;
use MyProject\Languages\Oval; // Apparantly Oval is also a language!
// Error!

use MyProject\Shapes\Oval as OvalShape;
use MyProject\Languages\Oval as OvalLanguage;

namespace MyProject\Shapes;

// References MyProject\Shapes\Rectangle. Correct!
$a = new Rectangle();

// References MyProject\Shapes\Rectangle. Correct, but unneeded!
$a = new \MyProject\Shapes\Rectangle(); 

// References MyProject\Shapes\MyProject\Shapes\Rectangle. Incorrect!
$a = new MyProject\Shapes\Rectangle();

// Referencing StdClass from within a namespace requires a \ prefix
// since it is not defined in a namespace, meaning it is global.

// References StdClass. Correct!
$a = new \StdClass(); 

// References MyProject\Shapes\StdClass. Incorrect!
$a = new StdClass();