update docs

Author: Alex Ermashev

composer.json

@@ -6,10 +6,13 @@
   "keywords": [
     "esase",
     "tinyframework",
+    "microservices",
     "framework",
     "lightweight",
-    "service manager",
+    "servicemanager",
     "container",
+    "servicelocator",
+    "psr",
     "di"
   ],
   "support": {

docs/index.rst

@@ -0,0 +1,155 @@
+.. _index-service-manager-label:
+
+Service manager
+===============
+
+The Service Manager is a **service/object locator**, tasked with retrieving other objects.
+It fully compatible with the PSR's containers - https://www.php-fig.org/psr/psr-11/
+
+Installation
+------------
+
+Run the following to install this library:
+
+
+.. code-block:: bash
+
+    $ composer require esase/tiny-service-manager
+
+Shared services
+---------------
+
+The most frequently used type of services it's shared services or singletons.
+The service manager always keeps and retrieves only the one instance of an object.
+It means you may reduce consuming of the memory and keep the state in a one object.
+
+--------------
+Shared example
+--------------
+
+.. code-block:: php
+
+    <?php
+
+        use Tiny\ServiceManager\ServiceManager;
+        use stdClass;
+
+        $serviceManager = new ServiceManager([
+            // pass a service name and it's factory
+            'TestService' => function() {
+                return new stdClass();
+            }
+        ]);
+
+        var_dump($serviceManager->has('TestService')); // prints `true`
+
+        $service1 = $serviceManager->get('TestService');
+        $service2 = $serviceManager->get('TestService');
+
+        var_dump($service1 === $service2); // prints `true`
+
+Discrete services
+-----------------
+
+Some times we don't need singletons, we need to retrieve a new object instance whenever we get it from the service manager.
+
+.. code-block:: php
+
+    <?php
+
+        use Tiny\ServiceManager\ServiceManager;
+        use stdClass;
+
+        // the constructor accepts  discrete services as a second parameter
+        $serviceManager = new ServiceManager([], [
+            // pass a service name and it's factory
+            'TestService' => function() { // now this is not a shared service
+                return new stdClass();
+            }
+        ]);
+
+        var_dump($serviceManager->has('TestService')); // prints `true`
+
+        $service1 = $serviceManager->get('TestService');
+        $service2 = $serviceManager->get('TestService');
+
+        var_dump($service1 === $service2); // prints `false` they are different
+
+Factories
+---------
+
+There are two types of factories which you can use for building you objects: :code:`Closure` and :code:`Class factories`
+
+---------------
+Closure example
+---------------
+
+The closure it's just an `anonymous` (or `lambda`) function which is called for building an object:
+
+.. code-block:: php
+
+    <?php
+
+        use Tiny\ServiceManager\ServiceManager;
+        use stdClass;
+
+        $serviceManager = new ServiceManager([
+            TestService::class => function(
+                ServiceManager $serviceManager,
+                string $targetClass
+            ) {
+                return new stdClass();
+            }
+        ]);
+
+It's a good practice to use a class name as key for services, :code:`TestService::class` in our case.
+Also as you can see the service manager always passes two parameters inside factories:
+
+- :code:`$serviceManager` - it's just a reference to it self which may be used for retrieving other dependencies.
+- :code:`$targetClass` - a class name which we are trying to build.
+
+---------------------
+Class factory example
+---------------------
+
+Remember each factory class must include :code:`__invoke` method.
+
+.. code-block:: php
+
+    <?php
+
+        use Tiny\ServiceManager\ServiceManager;
+
+        $serviceManager = new ServiceManager([], [
+            TestService::class => TestServiceFactory::class
+        ]);
+
+        class TestServiceFactory
+        {
+            public function __invoke(
+                ServiceManager $serviceManager,
+                string $targetClass
+            ): TestService {
+                // we even may inject different services
+                return new TestService(
+                    $serviceManager->get(OtherService::class)
+                    ...
+                );
+            }
+        }
+
+If you don't need to provide extra dependencies in you service you may use a default factory class,
+which just creates you service:
+
+.. code-block:: php
+
+    <?php
+
+        use Tiny\ServiceManager\ServiceManager;
+        use Tiny\ServiceManager\Factory\InvokableFactory;
+
+        $serviceManager = new ServiceManager([], [
+            TestService::class => InvokableFactory::class
+        ]);
+
+        ...

src/ServiceManager.php

@@ -96,7 +96,7 @@ public function get($id)
      *
      * @return bool
      */
-    public function has($id): bool
+    public function has($id)
     {
         if (isset($this->sharedServices[$id])
             || isset($this->discreteServices[$id])