PHP中的特征是否受命名空间的影响？

From the PHP documentation:

only four types of code are affected by namespaces: classes, interfaces, functions and constants.

But, it seems to me that TRAITS are also affected:

namespace FOO;

trait fooFoo {}

namespace BAR;

class baz
{
    use fooFoo; // Fatal error: Trait 'BAR\fooFoo' not found in
}

Am I wrong?

I think they are affected as well. Look at some of the comments on the php.net page.

The first comment:

Note that the "use" operator for traits (inside a class) and the "use" operator for namespaces (outside the class) resolve names differently. "use" for namespaces always sees its arguments as absolute (starting at the global namespace):

<?php
namespace Foo\Bar;
use Foo\Test;  // means \Foo\Test - the initial \ is optional
?>

On the other hand, "use" for traits respects the current namespace:

<?php
namespace Foo\Bar;
class SomeClass {
    use Foo\Test;   // means \Foo\Bar\Foo\Test
}
?>

In my experience if this piece of code you pasted resides in different files/folders and you use the spl_autoload_register function to load classes you need to do it like this:

  //file is in FOO/FooFoo.php
  namespace FOO;
  trait fooFoo {}

  //file is in BAR/baz.php
  namespace BAR;
  class baz
  {
   use \FOO\fooFoo; // note the backslash at the beginning, use must be in the class itself
  }

Yes, they are.

Import the trait with use outside the class for PSR-4 autoloading.

Then use the trait name inside the class.

namespace Example\Controllers;

use Example\Traits\MyTrait;

class Example {
    use MyTrait;

    // Do something
}

Or just use the Trait with full namespace:

namespace Example\Controllers;

class Example {
    use \Example\Traits\MyTrait;

    // Do something
}