diff --git a/.scrutinizer.yml b/.scrutinizer.yml
index cf46d83..c5d5b38 100644
--- a/.scrutinizer.yml
+++ b/.scrutinizer.yml
@@ -24,7 +24,7 @@ tools:
     php_code_coverage: false
     php_code_sniffer:
         config:
-            standard: PSR2
+            standard: PSR12
         filter:
             paths: ['src']
     php_loc:
diff --git a/.travis.yml b/.travis.yml
index 93a02ab..b1b93c5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,6 @@
 language: php
 
 php:
-    - 7.0
-    - 7.1
     - 7.2
     - 7.3
     - 7.4
diff --git a/README.md b/README.md
index 3c38f7b..48aa393 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,11 @@
 [![Quality Score](https://img.shields.io/scrutinizer/g/thephpleague/container.svg?style=flat-square)](https://scrutinizer-ci.com/g/thephpleague/container)
 [![Total Downloads](https://img.shields.io/packagist/dt/league/container.svg?style=flat-square)](https://packagist.org/packages/league/container)
 
-This package is compliant with [PSR-1], [PSR-2], [PSR-4] and [PSR-11]. If you notice compliance oversights, please send a patch via pull request.
+This package is compliant with [PSR-1], [PSR-2], [PSR-12], [PSR-4] and [PSR-11]. If you notice compliance oversights, please send a patch via pull request.
 
 [PSR-1]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-1-basic-coding-standard.md
 [PSR-2]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
+[PSR-12]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-12-extended-coding-style-guide.md
 [PSR-4]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader.md
 [PSR-11]: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-11-container.md
 
@@ -27,10 +28,9 @@ $ composer require league/container
 
 The following versions of PHP are supported by this version.
 
-* PHP 7.0
-* PHP 7.1
 * PHP 7.2
 * PHP 7.3
+* PHP 7.4
 
 ## Documentation
 
@@ -40,6 +40,7 @@ Contribute to this documentation in the [docs/](https://github.com/thephpleague/
 
 ## Testing
 
+Testing includes PHPUnit and PHPStan (Level 7).
 ``` bash
 $ composer test
 ```
diff --git a/composer.json b/composer.json
index 5b4125f..64f7881 100644
--- a/composer.json
+++ b/composer.json
@@ -21,12 +21,13 @@
         }
     ],
     "require": {
-        "php": "^7.0",
+        "php": "^7.2",
         "psr/container": "^1.0"
     },
     "require-dev": {
         "phpunit/phpunit" : "^6.0",
-        "squizlabs/php_codesniffer": "^3.3"
+        "squizlabs/php_codesniffer": "^3.3",
+        "phpstan/phpstan": "^0.11.8"
     },
     "provide": {
         "psr/container-implementation": "^1.0"
@@ -53,7 +54,8 @@
     },
     "scripts": {
         "test": [
-            "phpunit"
+            "phpunit",
+            "phpstan analyse --level 7 src"
         ]
     }
 }
diff --git a/phpcs.xml b/phpcs.xml
deleted file mode 100644
index 888ade9..0000000
--- a/phpcs.xml
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0"?>
-<ruleset name="PSR2-PHP7">
-    <description>PSR2 ruleset ignoring only grouped use statements.</description>
-     <rule ref="PSR2">
-         <exclude name="PSR2.Namespaces.UseDeclaration"/>
-     </rule>
-    <exclude-pattern>*/vendor/*</exclude-pattern>
-    <exclude-pattern>*.js</exclude-pattern>
-    <exclude-pattern>*.css</exclude-pattern>
-</ruleset>
diff --git a/src/Argument/RawArgumentInterface.php b/src/Argument/ArgumentInterface.php
similarity index 72%
rename from src/Argument/RawArgumentInterface.php
rename to src/Argument/ArgumentInterface.php
index 14157de..e6db634 100644
--- a/src/Argument/RawArgumentInterface.php
+++ b/src/Argument/ArgumentInterface.php
@@ -1,8 +1,10 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container\Argument;
 
-interface RawArgumentInterface
+interface ArgumentInterface
 {
     /**
      * Return the value of the raw argument.
diff --git a/src/Argument/ArgumentResolverInterface.php b/src/Argument/ArgumentResolverInterface.php
index 54b3236..c206922 100644
--- a/src/Argument/ArgumentResolverInterface.php
+++ b/src/Argument/ArgumentResolverInterface.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container\Argument;
 
@@ -14,7 +16,7 @@ interface ArgumentResolverInterface extends ContainerAwareInterface
      *
      * @return array
      */
-    public function resolveArguments(array $arguments) : array;
+    public function resolveArguments(array $arguments): array;
 
     /**
      * Resolves the correct arguments to be passed to a method.
@@ -24,5 +26,5 @@ public function resolveArguments(array $arguments) : array;
      *
      * @return array
      */
-    public function reflectArguments(ReflectionFunctionAbstract $method, array $args = []) : array;
+    public function reflectArguments(ReflectionFunctionAbstract $method, array $args = []): array;
 }
diff --git a/src/Argument/ArgumentResolverTrait.php b/src/Argument/ArgumentResolverTrait.php
index 7ae00e2..b60aff0 100644
--- a/src/Argument/ArgumentResolverTrait.php
+++ b/src/Argument/ArgumentResolverTrait.php
@@ -1,9 +1,11 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container\Argument;
 
-use League\Container\Container;
 use League\Container\Exception\{ContainerException, NotFoundException};
+use League\Container\DefinitionContainerInterface;
 use League\Container\ReflectionContainer;
 use Psr\Container\ContainerInterface;
 use ReflectionFunctionAbstract;
@@ -14,41 +16,30 @@ trait ArgumentResolverTrait
     /**
      * {@inheritdoc}
      */
-    public function resolveArguments(array $arguments) : array
+    public function resolveArguments(array $arguments): array
     {
+        try {
+            $container = $this->getContainer();
+        } catch (ContainerException $e) {
+            $container = ($this instanceof ReflectionContainer) ? $this : null;
+        }
+
         foreach ($arguments as &$arg) {
-            if ($arg instanceof RawArgumentInterface) {
+            if ($arg instanceof ArgumentInterface) {
                 $arg = $arg->getValue();
                 continue;
             }
 
-            if ($arg instanceof ClassNameInterface) {
-                $arg = $arg->getValue();
-            }
-
             if (! is_string($arg)) {
                  continue;
             }
 
-            $container = null;
-
-            try {
-                $container = $this->getLeagueContainer();
-            } catch (ContainerException $e) {
-                if ($this instanceof ReflectionContainer) {
-                    $container = $this;
-                }
-            }
-
-
-            if ($container !== null && $container->has($arg)) {
+            if ($container instanceof ContainerInterface && $container->has($arg)) {
                 $arg = $container->get($arg);
 
-                if ($arg instanceof RawArgumentInterface) {
+                if ($arg instanceof ArgumentInterface) {
                     $arg = $arg->getValue();
                 }
-
-                continue;
             }
         }
 
@@ -58,7 +49,7 @@ public function resolveArguments(array $arguments) : array
     /**
      * {@inheritdoc}
      */
-    public function reflectArguments(ReflectionFunctionAbstract $method, array $args = []) : array
+    public function reflectArguments(ReflectionFunctionAbstract $method, array $args = []): array
     {
         $arguments = array_map(function (ReflectionParameter $param) use ($method, $args) {
             $name  = $param->getName();
@@ -87,12 +78,9 @@ public function reflectArguments(ReflectionFunctionAbstract $method, array $args
     }
 
     /**
-     * @return ContainerInterface
-     */
-    abstract public function getContainer() : ContainerInterface;
-
-    /**
-     * @return Container
+     * Get the container.
+     *
+     * @return DefinitionContainerInterface
      */
-    abstract public function getLeagueContainer() : Container;
+    abstract public function getContainer(): DefinitionContainerInterface;
 }
diff --git a/src/Argument/ClassName.php b/src/Argument/ClassName.php
deleted file mode 100644
index d468fd4..0000000
--- a/src/Argument/ClassName.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace League\Container\Argument;
-
-class ClassName implements ClassNameInterface
-{
-    /**
-     * @var string
-     */
-    protected $value;
-
-    /**
-     * Construct.
-     *
-     * @param string $value
-     */
-    public function __construct(string $value)
-    {
-        $this->value = $value;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function getValue() : string
-    {
-        return $this->value;
-    }
-}
diff --git a/src/Argument/ClassNameInterface.php b/src/Argument/ClassNameInterface.php
deleted file mode 100644
index e27d118..0000000
--- a/src/Argument/ClassNameInterface.php
+++ /dev/null
@@ -1,13 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace League\Container\Argument;
-
-interface ClassNameInterface
-{
-    /**
-     * Return the class name.
-     *
-     * @return string
-     */
-    public function getValue() : string;
-}
diff --git a/src/Argument/RawArgument.php b/src/Argument/RawArgument.php
deleted file mode 100644
index 46319ca..0000000
--- a/src/Argument/RawArgument.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace League\Container\Argument;
-
-class RawArgument implements RawArgumentInterface
-{
-    /**
-     * @var mixed
-     */
-    protected $value;
-
-    /**
-     * Construct.
-     *
-     * @param mixed $value
-     */
-    public function __construct($value)
-    {
-        $this->value = $value;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function getValue()
-    {
-        return $this->value;
-    }
-}
diff --git a/src/Container.php b/src/Container.php
index cca5fb0..684a862 100644
--- a/src/Container.php
+++ b/src/Container.php
@@ -1,18 +1,16 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container;
 
 use League\Container\Definition\{DefinitionAggregate, DefinitionInterface, DefinitionAggregateInterface};
 use League\Container\Exception\{NotFoundException, ContainerException};
 use League\Container\Inflector\{InflectorAggregate, InflectorInterface, InflectorAggregateInterface};
-use League\Container\ServiceProvider\{
-    ServiceProviderAggregate,
-    ServiceProviderAggregateInterface,
-    ServiceProviderInterface
-};
+use League\Container\ServiceProvider\{ServiceProviderAggregate, ServiceProviderAggregateInterface};
 use Psr\Container\ContainerInterface;
 
-class Container implements ContainerInterface
+class Container implements DefinitionContainerInterface
 {
     /**
      * @var boolean
@@ -47,13 +45,13 @@ class Container implements ContainerInterface
      * @param InflectorAggregateInterface|null       $inflectors
      */
     public function __construct(
-        DefinitionAggregateInterface      $definitions = null,
+        DefinitionAggregateInterface $definitions = null,
         ServiceProviderAggregateInterface $providers = null,
-        InflectorAggregateInterface       $inflectors = null
+        InflectorAggregateInterface $inflectors = null
     ) {
-        $this->definitions = $definitions ?? new DefinitionAggregate;
-        $this->providers   = $providers   ?? new ServiceProviderAggregate;
-        $this->inflectors  = $inflectors  ?? new InflectorAggregate;
+        $this->definitions = $definitions ?? new DefinitionAggregate();
+        $this->providers   = $providers   ?? new ServiceProviderAggregate();
+        $this->inflectors  = $inflectors  ?? new InflectorAggregate();
 
         if ($this->definitions instanceof ContainerAwareInterface) {
             $this->definitions->setLeagueContainer($this);
@@ -69,15 +67,9 @@ public function __construct(
     }
 
     /**
-     * Add an item to the container.
-     *
-     * @param string  $id
-     * @param mixed   $concrete
-     * @param boolean $shared
-     *
-     * @return DefinitionInterface
+     * {@inheritdoc}
      */
-    public function add(string $id, $concrete = null, bool $shared = null) : DefinitionInterface
+    public function add(string $id, $concrete = null, bool $shared = null): DefinitionInterface
     {
         $concrete = $concrete ?? $id;
         $shared = $shared ?? $this->defaultToShared;
@@ -86,14 +78,9 @@ public function add(string $id, $concrete = null, bool $shared = null) : Definit
     }
 
     /**
-     * Proxy to add with shared as true.
-     *
-     * @param string $id
-     * @param mixed  $concrete
-     *
-     * @return DefinitionInterface
+     * {@inheritdoc}
      */
-    public function share(string $id, $concrete = null) : DefinitionInterface
+    public function share(string $id, $concrete = null): DefinitionInterface
     {
         return $this->add($id, $concrete, true);
     }
@@ -105,7 +92,7 @@ public function share(string $id, $concrete = null) : DefinitionInterface
      *
      * @return self
      */
-    public function defaultToShared(bool $shared = true) : ContainerInterface
+    public function defaultToShared(bool $shared = true): ContainerInterface
     {
         $this->defaultToShared = $shared;
 
@@ -113,13 +100,9 @@ public function defaultToShared(bool $shared = true) : ContainerInterface
     }
 
     /**
-     * Get a definition to extend.
-     *
-     * @param string $id [description]
-     *
-     * @return DefinitionInterface
+     * {@inheritdoc}
      */
-    public function extend(string $id) : DefinitionInterface
+    public function extend(string $id): DefinitionInterface
     {
         if ($this->providers->provides($id)) {
             $this->providers->register($id);
@@ -135,16 +118,11 @@ public function extend(string $id) : DefinitionInterface
     }
 
     /**
-     * Add a service provider.
-     *
-     * @param ServiceProviderInterface|string $provider
-     *
-     * @return self
+     * {@inheritdoc}
      */
-    public function addServiceProvider($provider) : self
+    public function addServiceProvider($provider): DefinitionContainerInterface
     {
         $this->providers->add($provider);
-
         return $this;
     }
 
@@ -191,7 +169,7 @@ public function get($id, bool $new = false)
     /**
      * {@inheritdoc}
      */
-    public function has($id) : bool
+    public function has($id): bool
     {
         if ($this->definitions->has($id)) {
             return true;
@@ -215,14 +193,9 @@ public function has($id) : bool
     }
 
     /**
-     * Allows for manipulation of specific types on resolution.
-     *
-     * @param string        $type
-     * @param callable|null $callback
-     *
-     * @return InflectorInterface
+     * {@inheritdoc}
      */
-    public function inflector(string $type, callable $callback = null) : InflectorInterface
+    public function inflector(string $type, callable $callback = null): InflectorInterface
     {
         return $this->inflectors->add($type, $callback);
     }
@@ -235,7 +208,7 @@ public function inflector(string $type, callable $callback = null) : InflectorIn
      *
      * @return self
      */
-    public function delegate(ContainerInterface $container) : self
+    public function delegate(ContainerInterface $container): self
     {
         $this->delegates[] = $container;
 
diff --git a/src/ContainerAwareInterface.php b/src/ContainerAwareInterface.php
index 870bfa3..c61f03f 100644
--- a/src/ContainerAwareInterface.php
+++ b/src/ContainerAwareInterface.php
@@ -1,40 +1,24 @@
-<?php declare(strict_types=1);
+<?php
 
-namespace League\Container;
+declare(strict_types=1);
 
-use Psr\Container\ContainerInterface;
+namespace League\Container;
 
 interface ContainerAwareInterface
 {
     /**
      * Set a container
      *
-     * @param ContainerInterface $container
+     * @param DefinitionContainerInterface $container
      *
      * @return self
      */
-    public function setContainer(ContainerInterface $container) : self;
+    public function setContainer(DefinitionContainerInterface $container): self;
 
     /**
      * Get the container
      *
-     * @return ContainerInterface
-     */
-    public function getContainer() : ContainerInterface;
-
-    /**
-     * Set a container. This will be removed in favour of setContainer receiving Container in next major release.
-     *
-     * @param Container $container
-     *
-     * @return self
-     */
-    public function setLeagueContainer(Container $container) : self;
-
-    /**
-     * Get the container. This will be removed in favour of getContainer returning Container in next major release.
-     *
-     * @return Container
+     * @return DefinitionContainerInterface
      */
-    public function getLeagueContainer() : Container;
+    public function getContainer(): DefinitionContainerInterface;
 }
diff --git a/src/ContainerAwareTrait.php b/src/ContainerAwareTrait.php
index da6030a..1667161 100644
--- a/src/ContainerAwareTrait.php
+++ b/src/ContainerAwareTrait.php
@@ -1,14 +1,15 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container;
 
 use League\Container\Exception\ContainerException;
-use Psr\Container\ContainerInterface;
 
 trait ContainerAwareTrait
 {
     /**
-     * @var ContainerInterface
+     * @var DefinitionContainerInterface
      */
     protected $container;
 
@@ -20,57 +21,27 @@ trait ContainerAwareTrait
     /**
      * Set a container.
      *
-     * @param ContainerInterface $container
+     * @param DefinitionContainerInterface $container
      *
-     * @return self
+     * @return ContainerAwareInterface
      */
-    public function setContainer(ContainerInterface $container) : ContainerAwareInterface
+    public function setContainer(DefinitionContainerInterface $container): ContainerAwareInterface
     {
         $this->container = $container;
-
         return $this;
     }
 
     /**
      * Get the container.
      *
-     * @return ContainerInterface
+     * @return DefinitionContainerInterface
      */
-    public function getContainer() : ContainerInterface
+    public function getContainer(): DefinitionContainerInterface
     {
-        if ($this->container instanceof ContainerInterface) {
+        if ($this->container instanceof DefinitionContainerInterface) {
             return $this->container;
         }
 
         throw new ContainerException('No container implementation has been set.');
     }
-
-    /**
-     * Set a container.
-     *
-     * @param Container $container
-     *
-     * @return self
-     */
-    public function setLeagueContainer(Container $container) : ContainerAwareInterface
-    {
-        $this->container = $container;
-        $this->leagueContainer = $container;
-
-        return $this;
-    }
-
-    /**
-     * Get the container.
-     *
-     * @return Container
-     */
-    public function getLeagueContainer() : Container
-    {
-        if ($this->leagueContainer instanceof Container) {
-            return $this->leagueContainer;
-        }
-
-        throw new ContainerException('No container implementation has been set.');
-    }
 }
diff --git a/src/Definition/Definition.php b/src/Definition/Definition.php
index 19a329e..401ccb5 100644
--- a/src/Definition/Definition.php
+++ b/src/Definition/Definition.php
@@ -1,9 +1,11 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container\Definition;
 
 use League\Container\Argument\{
-    ArgumentResolverInterface, ArgumentResolverTrait, ClassNameInterface, RawArgumentInterface
+    ArgumentResolverInterface, ArgumentResolverTrait, ClassNameInterface, ArgumentInterface
 };
 use League\Container\ContainerAwareTrait;
 use ReflectionClass;
@@ -66,17 +68,16 @@ public function __construct(string $id, $concrete = null)
     /**
      * {@inheritdoc}
      */
-    public function addTag(string $tag) : DefinitionInterface
+    public function addTag(string $tag): DefinitionInterface
     {
-        $this->tags[$tag] = true;
-
+        $this->tags[] = $tag;
         return $this;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function hasTag(string $tag) : bool
+    public function hasTag(string $tag): bool
     {
         return isset($this->tags[$tag]);
     }
@@ -84,17 +85,16 @@ public function hasTag(string $tag) : bool
     /**
      * {@inheritdoc}
      */
-    public function setAlias(string $id) : DefinitionInterface
+    public function setAlias(string $id): DefinitionInterface
     {
         $this->alias = $id;
-
         return $this;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function getAlias() : string
+    public function getAlias(): string
     {
         return $this->alias;
     }
@@ -102,17 +102,16 @@ public function getAlias() : string
     /**
      * {@inheritdoc}
      */
-    public function setShared(bool $shared = true) : DefinitionInterface
+    public function setShared(bool $shared = true): DefinitionInterface
     {
         $this->shared = $shared;
-
         return $this;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function isShared() : bool
+    public function isShared(): bool
     {
         return $this->shared;
     }
@@ -128,28 +127,26 @@ public function getConcrete()
     /**
      * {@inheritdoc}
      */
-    public function setConcrete($concrete) : DefinitionInterface
+    public function setConcrete($concrete): DefinitionInterface
     {
         $this->concrete = $concrete;
         $this->resolved = null;
-
         return $this;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function addArgument($arg) : DefinitionInterface
+    public function addArgument($arg): DefinitionInterface
     {
         $this->arguments[] = $arg;
-
         return $this;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function addArguments(array $args) : DefinitionInterface
+    public function addArguments(array $args): DefinitionInterface
     {
         foreach ($args as $arg) {
             $this->addArgument($arg);
@@ -161,7 +158,7 @@ public function addArguments(array $args) : DefinitionInterface
     /**
      * {@inheritdoc}
      */
-    public function addMethodCall(string $method, array $args = []) : DefinitionInterface
+    public function addMethodCall(string $method, array $args = []): DefinitionInterface
     {
         $this->methods[] = [
             'method'    => $method,
@@ -174,7 +171,7 @@ public function addMethodCall(string $method, array $args = []) : DefinitionInte
     /**
      * {@inheritdoc}
      */
-    public function addMethodCalls(array $methods = []) : DefinitionInterface
+    public function addMethodCalls(array $methods = []): DefinitionInterface
     {
         foreach ($methods as $method => $args) {
             $this->addMethodCall($method, $args);
@@ -190,7 +187,7 @@ public function resolve(bool $new = false)
     {
         $concrete = $this->concrete;
 
-        if ($this->isShared() && $this->resolved !== null && $new === false) {
+        if ($new === false && $this->resolved !== null && $this->isShared()) {
             return $this->resolved;
         }
 
@@ -198,9 +195,8 @@ public function resolve(bool $new = false)
             $concrete = $this->resolveCallable($concrete);
         }
 
-        if ($concrete instanceof RawArgumentInterface) {
+        if ($concrete instanceof ArgumentInterface) {
             $this->resolved = $concrete->getValue();
-
             return $concrete->getValue();
         }
 
@@ -231,7 +227,6 @@ public function resolve(bool $new = false)
     protected function resolveCallable(callable $concrete)
     {
         $resolved = $this->resolveArguments($this->arguments);
-
         return call_user_func_array($concrete, $resolved);
     }
 
@@ -248,7 +243,6 @@ protected function resolveClass(string $concrete)
     {
         $resolved   = $this->resolveArguments($this->arguments);
         $reflection = new ReflectionClass($concrete);
-
         return $reflection->newInstanceArgs($resolved);
     }
 
@@ -263,7 +257,6 @@ protected function invokeMethods($instance)
     {
         foreach ($this->methods as $method) {
             $args = $this->resolveArguments($method['arguments']);
-
             /** @var callable $callable */
             $callable = [$instance, $method['method']];
             call_user_func_array($callable, $args);
diff --git a/src/Definition/DefinitionAggregate.php b/src/Definition/DefinitionAggregate.php
index 3c4fb8d..a7f8acb 100644
--- a/src/Definition/DefinitionAggregate.php
+++ b/src/Definition/DefinitionAggregate.php
@@ -22,7 +22,7 @@ class DefinitionAggregate implements DefinitionAggregateInterface
      */
     public function __construct(array $definitions = [])
     {
-        $this->definitions = array_filter($definitions, function ($definition) {
+        $this->definitions = array_filter($definitions, static function ($definition) {
             return ($definition instanceof DefinitionInterface);
         });
     }
@@ -32,14 +32,11 @@ public function __construct(array $definitions = [])
      */
     public function add(string $id, $definition, bool $shared = false) : DefinitionInterface
     {
-        if (!$definition instanceof DefinitionInterface) {
+        if (false === ($definition instanceof DefinitionInterface)) {
             $definition = new Definition($id, $definition);
         }
 
-        $this->definitions[] = $definition
-            ->setAlias($id)
-            ->setShared($shared)
-        ;
+        $this->definitions[] = $definition->setAlias($id)->setShared($shared);
 
         return $definition;
     }
@@ -115,10 +112,6 @@ public function resolveTagged(string $tag, bool $new = false) : array
      */
     public function getIterator() : Generator
     {
-        $count = count($this->definitions);
-
-        for ($i = 0; $i < $count; $i++) {
-            yield $this->definitions[$i];
-        }
+        yield from $this->definitions;
     }
 }
diff --git a/src/Definition/DefinitionAggregateInterface.php b/src/Definition/DefinitionAggregateInterface.php
index 3e9876d..783dab7 100644
--- a/src/Definition/DefinitionAggregateInterface.php
+++ b/src/Definition/DefinitionAggregateInterface.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container\Definition;
 
@@ -16,7 +18,7 @@ interface DefinitionAggregateInterface extends ContainerAwareInterface, Iterator
      *
      * @return DefinitionInterface
      */
-    public function add(string $id, $definition, bool $shared = false) : DefinitionInterface;
+    public function add(string $id, $definition, bool $shared = false): DefinitionInterface;
 
     /**
      * Checks whether alias exists as definition.
@@ -25,7 +27,7 @@ public function add(string $id, $definition, bool $shared = false) : DefinitionI
      *
      * @return boolean
      */
-    public function has(string $id) : bool;
+    public function has(string $id): bool;
 
     /**
      * Checks whether tag exists as definition.
@@ -34,7 +36,7 @@ public function has(string $id) : bool;
      *
      * @return boolean
      */
-    public function hasTag(string $tag) : bool;
+    public function hasTag(string $tag): bool;
 
     /**
      * Get the definition to be extended.
@@ -43,7 +45,7 @@ public function hasTag(string $tag) : bool;
      *
      * @return DefinitionInterface
      */
-    public function getDefinition(string $id) : DefinitionInterface;
+    public function getDefinition(string $id): DefinitionInterface;
 
     /**
      * Resolve and build a concrete value from an id/alias.
diff --git a/src/Definition/DefinitionInterface.php b/src/Definition/DefinitionInterface.php
index 244c49f..bc377d6 100644
--- a/src/Definition/DefinitionInterface.php
+++ b/src/Definition/DefinitionInterface.php
@@ -13,7 +13,7 @@ interface DefinitionInterface extends ContainerAwareInterface
      *
      * @return self
      */
-    public function addTag(string $tag) : DefinitionInterface;
+    public function addTag(string $tag): DefinitionInterface;
 
     /**
      * Does the definition have a tag?
@@ -22,7 +22,7 @@ public function addTag(string $tag) : DefinitionInterface;
      *
      * @return boolean
      */
-    public function hasTag(string $tag) : bool;
+    public function hasTag(string $tag): bool;
 
     /**
      * Set the alias of the definition.
@@ -31,14 +31,14 @@ public function hasTag(string $tag) : bool;
      *
      * @return DefinitionInterface
      */
-    public function setAlias(string $id) : DefinitionInterface;
+    public function setAlias(string $id): DefinitionInterface;
 
     /**
      * Get the alias of the definition.
      *
      * @return string
      */
-    public function getAlias() : string;
+    public function getAlias(): string;
 
     /**
      * Set whether this is a shared definition.
@@ -47,14 +47,14 @@ public function getAlias() : string;
      *
      * @return self
      */
-    public function setShared(bool $shared) : DefinitionInterface;
+    public function setShared(bool $shared): DefinitionInterface;
 
     /**
      * Is this a shared definition?
      *
      * @return boolean
      */
-    public function isShared() : bool;
+    public function isShared(): bool;
 
     /**
      * Get the concrete of the definition.
@@ -70,7 +70,7 @@ public function getConcrete();
      *
      * @return DefinitionInterface
      */
-    public function setConcrete($concrete) : DefinitionInterface;
+    public function setConcrete($concrete): DefinitionInterface;
 
     /**
      * Add an argument to be injected.
@@ -79,7 +79,7 @@ public function setConcrete($concrete) : DefinitionInterface;
      *
      * @return self
      */
-    public function addArgument($arg) : DefinitionInterface;
+    public function addArgument($arg): DefinitionInterface;
 
     /**
      * Add multiple arguments to be injected.
@@ -88,7 +88,7 @@ public function addArgument($arg) : DefinitionInterface;
      *
      * @return self
      */
-    public function addArguments(array $args) : DefinitionInterface;
+    public function addArguments(array $args): DefinitionInterface;
 
     /**
      * Add a method to be invoked
@@ -98,7 +98,7 @@ public function addArguments(array $args) : DefinitionInterface;
      *
      * @return self
      */
-    public function addMethodCall(string $method, array $args = []) : DefinitionInterface;
+    public function addMethodCall(string $method, array $args = []): DefinitionInterface;
 
     /**
      * Add multiple methods to be invoked
@@ -107,7 +107,7 @@ public function addMethodCall(string $method, array $args = []) : DefinitionInte
      *
      * @return self
      */
-    public function addMethodCalls(array $methods = []) : DefinitionInterface;
+    public function addMethodCalls(array $methods = []): DefinitionInterface;
 
     /**
      * Handle instantiation and manipulation of value and return.
diff --git a/src/ReflectionContainer.php b/src/ReflectionContainer.php
index 1fc7637..3837073 100644
--- a/src/ReflectionContainer.php
+++ b/src/ReflectionContainer.php
@@ -1,4 +1,6 @@
-<?php declare(strict_types=1);
+<?php
+
+declare(strict_types=1);
 
 namespace League\Container;
 
@@ -18,15 +20,23 @@ class ReflectionContainer implements ArgumentResolverInterface, ContainerInterfa
     /**
      * @var boolean
      */
-    protected $cacheResolutions = false;
+    protected $cacheResolutions;
 
     /**
-     * Cache of resolutions.
-     *
      * @var array
      */
     protected $cache = [];
 
+    /**
+     * Construct.
+     *
+     * @param boolean $cacheResolutions
+     */
+    public function __construct(bool $cacheResolutions = false)
+    {
+        $this->cacheResolutions = $cacheResolutions;
+    }
+
     /**
      * {@inheritdoc}
      *
@@ -48,7 +58,7 @@ public function get($id, array $args = [])
         $construct = $reflector->getConstructor();
 
         $resolution = $construct === null
-            ? new $id
+            ? new $id()
             : $resolution = $reflector->newInstanceArgs($this->reflectArguments($construct, $args))
         ;
 
@@ -62,7 +72,7 @@ public function get($id, array $args = [])
     /**
      * {@inheritdoc}
      */
-    public function has($id) : bool
+    public function has($id): bool
     {
         return class_exists($id);
     }
@@ -99,7 +109,6 @@ public function call(callable $callable, array $args = [])
 
         if (is_object($callable)) {
             $reflection = new ReflectionMethod($callable, '__invoke');
-
             return $reflection->invokeArgs($callable, $this->reflectArguments($reflection, $args));
         }
 
@@ -107,19 +116,4 @@ public function call(callable $callable, array $args = [])
 
         return $reflection->invokeArgs($this->reflectArguments($reflection, $args));
     }
-
-    /**
-     * Whether the container should default to caching resolutions and returning
-     * the cache on following calls.
-     *
-     * @param boolean $option
-     *
-     * @return self
-     */
-    public function cacheResolutions(bool $option = true) : ContainerInterface
-    {
-        $this->cacheResolutions = $option;
-
-        return $this;
-    }
 }
diff --git a/tests/Argument/ArgumentResolverTest.php b/tests/Argument/ArgumentResolverTest.php
index 5a9a179..b327ac0 100644
--- a/tests/Argument/ArgumentResolverTest.php
+++ b/tests/Argument/ArgumentResolverTest.php
@@ -1,8 +1,8 @@
 <?php declare(strict_types=1);
 
-namespace League\Container\Test;
+namespace League\Container\Test\Argument;
 
-use League\Container\Argument\{ArgumentResolverInterface, ArgumentResolverTrait, RawArgument};
+use League\Container\Argument\{ArgumentResolverInterface, ArgumentResolverTrait, Argument};
 use League\Container\{Container, ContainerAwareTrait};
 use PHPUnit\Framework\TestCase;
 use Psr\Container\NotFoundExceptionInterface;
@@ -24,10 +24,17 @@ public function testResolverResolvesFromContainer()
 
         $container = $this->getMockBuilder(Container::class)->getMock();
 
-        $container->expects($this->at(0))->method('has')->with($this->equalTo('alias1'))->willReturn(true);
+        $container
+            ->expects($this->at(0))
+            ->method('has')
+            ->with($this->equalTo('alias1'))
+            ->willReturn(true)
+        ;
+
         $container->expects($this->at(1))->method('get')->with($this->equalTo('alias1'))->willReturn($resolver);
         $container->expects($this->at(2))->method('has')->with($this->equalTo('alias2'))->willReturn(false);
 
+        /** @var Container $container */
         $resolver->setLeagueContainer($container);
 
         $args = $resolver->resolveArguments(['alias1', 'alias2']);
@@ -49,11 +56,12 @@ public function testResolverResolvesResolvesRawArguments()
         $container = $this->getMockBuilder(Container::class)->getMock();
 
         $container->expects($this->at(0))->method('has')->with($this->equalTo('alias1'))->willReturn(true);
-        $container->expects($this->at(1))->method('get')->with($this->equalTo('alias1'))->willReturn(new RawArgument('value1'));
+        $container->expects($this->at(1))->method('get')->with($this->equalTo('alias1'))->willReturn(new Argument('value1'));
 
+        /** @var Container $container */
         $resolver->setLeagueContainer($container);
 
-        $args = $resolver->resolveArguments(['alias1', new RawArgument('value2')]);
+        $args = $resolver->resolveArguments(['alias1', new Argument('value2')]);
 
         $this->assertSame('value1', $args[0]);
         $this->assertSame('value2', $args[1]);
@@ -94,6 +102,7 @@ public function testResolverResolvesArgumentsViaReflection()
             use ContainerAwareTrait;
         };
 
+        /** @var Container $container */
         $resolver->setLeagueContainer($container);
 
         $args = $resolver->reflectArguments($method, ['param3' => 'value3']);
@@ -124,6 +133,7 @@ public function testResolverThrowsExceptionWhenReflectionDoesNotResolve()
             use ContainerAwareTrait;
         };
 
+        /** @var ReflectionFunctionAbstract $method */
         $resolver->reflectArguments($method);
     }
 }
diff --git a/tests/Argument/ClassNameTest.php b/tests/Argument/ClassNameTest.php
index 29900aa..20d378b 100644
--- a/tests/Argument/ClassNameTest.php
+++ b/tests/Argument/ClassNameTest.php
@@ -1,6 +1,6 @@
 <?php declare(strict_types=1);
 
-namespace League\Container\Test;
+namespace League\Container\Test\Argument;
 
 use League\Container\Argument\ClassName;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Argument/RawArgumentTest.php b/tests/Argument/RawArgumentTest.php
index a7e52e2..3fac53b 100644
--- a/tests/Argument/RawArgumentTest.php
+++ b/tests/Argument/RawArgumentTest.php
@@ -1,8 +1,8 @@
 <?php declare(strict_types=1);
 
-namespace League\Container\Test;
+namespace League\Container\Test\Argument;
 
-use League\Container\Argument\RawArgument;
+use League\Container\Argument\Argument;
 use PHPUnit\Framework\TestCase;
 
 class RawArgumentTest extends TestCase
@@ -24,7 +24,7 @@ function () {
         ];
 
         foreach ($arguments as $expected) {
-            $argument = new RawArgument($expected);
+            $argument = new Argument($expected);
             $this->assertSame($expected, $argument->getValue());
         }
     }
diff --git a/tests/Definition/DefinitionTest.php b/tests/Definition/DefinitionTest.php
index 2cf7fd7..dbe97b6 100644
--- a/tests/Definition/DefinitionTest.php
+++ b/tests/Definition/DefinitionTest.php
@@ -2,7 +2,7 @@
 
 namespace League\Container\Test\Definition;
 
-use League\Container\Argument\{ClassName, RawArgument};
+use League\Container\Argument\{ClassName, Argument};
 use League\Container\Definition\Definition;
 use League\Container\Test\Asset\{Foo, FooCallable, Bar};
 use PHPUnit\Framework\TestCase;
@@ -32,7 +32,7 @@ public function testDefinitionResolvesClosureWithDefinedArgs()
     public function testDefinitionResolvesClosureReturningRawArgument()
     {
         $definition = new Definition('callable', function () {
-            return new RawArgument('hello world');
+            return new Argument('hello world');
         });
 
         $actual = $definition->resolve();
diff --git a/tests/Inflector/InflectorAggregateTest.php b/tests/Inflector/InflectorAggregateTest.php
index 1b829fc..7e6b94f 100644
--- a/tests/Inflector/InflectorAggregateTest.php
+++ b/tests/Inflector/InflectorAggregateTest.php
@@ -2,8 +2,8 @@
 
 namespace League\Container\Test\Inflector;
 
-use League\Container\ContaineAwareInterface;
-use League\Container\Inflector\{InflectorAggregate, Inflector};
+use League\Container\ContainerAwareInterface;
+use League\Container\Inflector\InflectorAggregate;
 use PHPUnit\Framework\TestCase;
 use League\Container\Container;
 
@@ -43,11 +43,11 @@ public function testAggregateAddsAndIteratesMultipleInflectors()
     public function testAggregateIteratesAndInflectsOnObject()
     {
         $aggregate      = new InflectorAggregate;
-        $containerAware = $this->getMockBuilder(ContaineAwareInterface::class)->setMethods(['setLeagueContainer'])->getMock();
+        $containerAware = $this->getMockBuilder(ContainerAwareInterface::class)->getMock();
         $container      = $this->getMockBuilder(Container::class)->getMock();
 
         $containerAware->expects($this->once())->method('setLeagueContainer')->with($this->equalTo($container));
-        $aggregate->add(ContaineAwareInterface::class)->invokeMethod('setLeagueContainer', [$container]);
+        $aggregate->add(ContainerAwareInterface::class)->invokeMethod('setLeagueContainer', [$container]);
         $aggregate->add('Ignored\Type');
 
         $aggregate->setLeagueContainer($container);