HttpKernel name can't be imported twice, if importing only Symfony\Component\HttpKernel\HttpKernel there will be problems later with HttpKernel subclasses (HttpKernel\Controller\ControllerResolver first and the others following). Could use 'use ... as ...' but I don't like it.

hrbonz · hrbonz · commit de69a874c1ec · 2012-02-07T04:48:25.000+01:00
diff --git a/book/part12.rst b/book/part12.rst
@@ -12,12 +12,11 @@ some code from the front controller to it::
 
     namespace Simplex;
 
-    use Symfony\Component\HttpKernel\HttpKernel;
     use Symfony\Component\Routing;
     use Symfony\Component\HttpKernel;
     use Symfony\Component\EventDispatcher\EventDispatcher;
 
-    class Framework extends HttpKernel
+    class Framework extends HttpKernel\HttpKernel
     {
         public function __construct($routes)
         {

Original file line number	Diff line number	Diff line change
`@@ -12,12 +12,11 @@ some code from the front controller to it::`
`12`	`12`
`13`	`13`	`namespace Simplex;`
`14`	`14`
`15`		`- use Symfony\Component\HttpKernel\HttpKernel;`
`16`	`15`	`use Symfony\Component\Routing;`
`17`	`16`	`use Symfony\Component\HttpKernel;`
`18`	`17`	`use Symfony\Component\EventDispatcher\EventDispatcher;`
`19`	`18`
`20`		`- class Framework extends HttpKernel`
	`19`	`+ class Framework extends HttpKernel\HttpKernel`
`21`	`20`	`{`
`22`	`21`	`public function __construct($routes)`
`23`	`22`	`{`