Accepts callable as first argument of Predis\Client::__construct().

Users can then use callables to wrap the creation and initialization
of the underlying connection with custom strategies:

CHANGELOG.md

@@ -11,6 +11,10 @@ v0.8.3 (2013-xx-xx)
   hash slots instead of 4096 to reflect this recent change from redis unstable
   ([see this commit](https://github.com/antirez/redis/commit/ebd666d)).
 
+- The constructor of `Predis\Client` now accepts a callable as first argument
+  returning `Predis\Connection\ConnectionInterface`. Users can create their
+  own self-contained strategies to create and set up the underlying connection.
+
 
 v0.8.2 (2013-02-03)
 ===============================================================================

lib/Predis/Client.php

@@ -100,6 +100,18 @@ class Client implements ClientInterface
             return $this->connections->createAggregated($connection, $parameters);
         }
 
+        if (is_callable($parameters)) {
+            $connection = call_user_func($parameters, $this->options);
+
+            if (!$connection instanceof ConnectionInterface) {
+                throw new \InvalidArgumentException(
+                    'Callable parameters must return instances of Predis\Connection\ConnectionInterface'
+                );
+            }
+
+            return $connection;
+        }
+
         return $this->connections->create($parameters);
     }
 

tests/Predis/ClientTest.php

@@ -197,6 +197,42 @@ class ClientTest extends StandardTestCase
         $this->assertSame($replication, $client->getConnection());
     }
 
+    /**
+     * @group disconnected
+     */
+    public function testConstructorWithCallableArgument()
+    {
+        $connection = $this->getMock('Predis\Connection\ConnectionInterface');
+
+        $callable = $this->getMock('stdClass', array('__invoke'));
+        $callable->expects($this->once())
+                 ->method('__invoke')
+                 ->with($this->isInstanceOf('Predis\Option\ClientOptions'))
+                 ->will($this->returnValue($connection));
+
+        $client = new Client($callable);
+
+        $this->assertSame($connection, $client->getConnection());
+    }
+
+    /**
+     * @group disconnected
+     * @expectedException InvalidArgumentException
+     * @expectedExceptionMessage Callable parameters must return instances of Predis\Connection\ConnectionInterface
+     */
+    public function testConstructorWithCallableArgumentButInvalidReturnType()
+    {
+        $wrongType = $this->getMock('stdClass');
+
+        $callable = $this->getMock('stdClass', array('__invoke'));
+        $callable->expects($this->once())
+                 ->method('__invoke')
+                 ->with($this->isInstanceOf('Predis\Option\ClientOptions'))
+                 ->will($this->returnValue($wrongType));
+
+        $client = new Client($callable);
+    }
+
     /**
      * @group disconnected
      */