变量中的PHP命名空间类

Question

Can anyone explain why the below code causes a "Cannot find class" error? Instantiating the class with the fully qualified name works, but eliminates the advantage of the "use" statement.

<?php

namespace
{
    use Foo\Bar;

    new Bar;    // Works

    $class = 'Foo\Bar'; 

    new $class; // Works

    $class = 'Bar';

    new $class; // "Cannot find class" error
}

namespace Foo
{
    class Bar {}
}

Thanks

Answer 1

Well, I suppose it's actually a feature. And aliases won't help here, for the same reasons:

Importing is performed at compile-time, and so does not affect dynamic class, function or constant names. [...]

<?php 
use My\Full\Classname as Another, My\Full\NSname;

$obj = new Another; // instantiates object of class My\Full\Classname
$a = 'Another'; 
$obj = new $a;      // instantiates object of class Another 
?>

And yes, it sorts of defeats the purpose of use with dynamic classes.