static init() for usability

README.md

@@ -47,7 +47,7 @@ $result = $stage3($stage2($stage1($payload)));
 
 Pipelines are implemented as immutable stage chains. When you pipe a new
 stage, a new pipeline will be created with the added stage. This makes
-pipelines easy to reuse, and minimizes side-effects.
+pipelines easy to reuse, and minimizes side effects.
 
 ## Usage
 
@@ -58,6 +58,12 @@ type-hint. So closures and anything that's invokable is good.
 $pipeline = (new Pipeline)->pipe(function ($payload) {
     return $payload * 10;
 });
+
+// or 
+
+$pipeline = Pipeline::init()->pipe(function ($payload) {
+    return $payload * 10;
+});
 ```
 
 ## Class based stages.
@@ -127,6 +133,8 @@ any given time.
 use League\Pipeline\PipelineBuilder;
 
 // Prepare the builder
+// $pipelineBuilder = PipelineBuilder::init()
+// or
 $pipelineBuilder = (new PipelineBuilder)
     ->add(new LogicalStage)
     ->add(new AnotherStage)

spec/PipelineBuilderSpec.php

@@ -14,6 +14,11 @@ function it_is_initializable()
         $this->shouldHaveType(PipelineBuilder::class);
     }
 
+    function it_is_static_initializable()
+    {
+        $this->shouldBeAnInstanceOf(get_class(PipelineBuilder::init()));
+    }
+
     function it_should_collect_operations_for_a_pipeline()
     {
         $this->add(function ($p) {

spec/PipelineSpec.php

@@ -2,13 +2,11 @@
 
 namespace spec\League\Pipeline;
 
-use InvalidArgumentException;
 use League\Pipeline\CallableStage;
 use League\Pipeline\Pipeline;
 use League\Pipeline\PipelineInterface;
 use League\Pipeline\Stub\StubStage;
 use PhpSpec\ObjectBehavior;
-use Prophecy\Argument;
 
 class PipelineSpec extends ObjectBehavior
 {
@@ -30,6 +28,12 @@ function it_should_compose_pipelines()
         $this->pipe($pipeline)->process('something')->shouldBe(10);
     }
 
+    function it_should_initiate_and_compose_pipelines()
+    {
+        $pipeline = Pipeline::init()->pipe(function () { return 10; });
+        $this->pipe($pipeline)->process('something')->shouldBe(10);
+    }
+
     function it_should_process_a_payload()
     {
         $operation = function ($payload) { return $payload + 1; };

src/Pipeline.php

@@ -8,7 +8,7 @@ class Pipeline implements PipelineInterface
     /**
      * @var callable[]
      */
-    private $stages = [];
+    private $stages;
 
     /**
      * @var ProcessorInterface
@@ -21,6 +21,11 @@ public function __construct(ProcessorInterface $processor = null, callable ...$s
         $this->stages = $stages;
     }
 
+    public static function init(ProcessorInterface $processor = null, callable ...$stages): PipelineInterface
+    {
+        return new self($processor, ...$stages);
+    }
+
     public function pipe(callable $stage): PipelineInterface
     {
         $pipeline = clone $this;

src/PipelineBuilder.php

@@ -10,6 +10,14 @@ class PipelineBuilder implements PipelineBuilderInterface
      */
     private $stages = [];
 
+    /**
+     * @return self
+     */
+    public static function init(): PipelineBuilderInterface
+    {
+        return new self();
+    }
+
     /**
      * @return self
      */

src/PipelineBuilderInterface.php

@@ -8,6 +8,7 @@ interface PipelineBuilderInterface
     /**
      * Add an stage.
      *
+     * @param callable $stage
      * @return self
      */
     public function add(callable $stage): PipelineBuilderInterface;

src/PipelineInterface.php

@@ -10,7 +10,7 @@ interface PipelineInterface extends StageInterface
      *
      * @return static
      */
-    public function pipe(callable $operation): PipelineInterface;
+    public function pipe(callable $stage): PipelineInterface;
 
     /**
      * Process the payload.