GDXbsv · July 3, 2018 21:10 · May 20, 2015 · May 20, 2015 · May 20, 2015 · May 20, 2015
diff --git a/README.md b/README.md
@@ -12,7 +12,7 @@ Mainly:
  - `function` is not testable in isolation if it isn't a pure function 
    without dependencies
 
-In order to "fix" the problems exposed above, and avoid global or static
+In order to _fix_ the problems exposed above, and avoid global or static
 scope pollution, two approaches are possible:
 
  - using a [`Closure`](http://php.net/manual/en/functions.anonymous.php), combined 
@@ -24,9 +24,10 @@ Few notes:
 
  - a class that only implements `__invoke` and `__construct` is basically 
    a `function` combined with a `functor`
- - a class can be easily tested in insulation
- - a `Closure` with dependencies cannot be tested in insulation
- - in order to make a `Closure` testable in insulation, it must be combined 
+
+ - a class can be easily tested in isolation
+ - a `Closure` with dependencies cannot be tested in isolation
+ - in order to make a `Closure` testable in isolation, it must be combined
    with a **higher order function**
  - there is no runtime difference between using a `Closure` and any object
    with an `__invoke` method defined in its class

diff --git a/__invoke.php b/__invoke.php
@@ -19,8 +19,6 @@ public function __invoke(User $user)
     }
 }
 
-// usage:
+// usage (PHP 7) - see http://3v4l.org/kPnLM:
 
-$login = new Login($sessionRepository);
-
-$login($user);
+$session = (new Login($sessionRepository))($user);
diff --git a/closure.php b/closure.php
@@ -17,4 +17,4 @@
 
 // usage (PHP 7) - see http://3v4l.org/kPnLM:
 
-$loginFactory(sessionRepository)($user);
+$session = $loginFactory(sessionRepository)($user);
diff --git a/function.php b/function.php
@@ -14,4 +14,4 @@ function login(User $user)
 
 // usage:
 
-login($user);
+$session = login($user);
diff --git a/README.md b/README.md
@@ -9,7 +9,7 @@ Mainly:
 
  - `function` cannot (should not) be used when side-effects occur
  - `function` does not work with dependency injection
- - `function` is not testable in insulation if it isn't a pure function 
+ - `function` is not testable in isolation if it isn't a pure function 
    without dependencies
 
 In order to "fix" the problems exposed above, and avoid global or static

diff --git a/README.md b/README.md
@@ -30,6 +30,9 @@ Few notes:
    with a **higher order function**
  - there is no runtime difference between using a `Closure` and any object
    with an `__invoke` method defined in its class
+ - in PHP, `$a = function () use (...) {}` simply means "call the constructor
+   of class `Closure` with these parameters and this body for `__invoke`",
+   so you end up with an object that implements `__invoke` anyway.
 
 Therefore, `object` + `__invoke` is much simpler and flexible than using 
 a `Closure`, whereas a `function` is not applicable in any context that 

diff --git a/README.md b/README.md
@@ -12,7 +12,7 @@ Mainly:
  - `function` is not testable in insulation if it isn't a pure function 
    without dependencies
 
-In order to "fix" the problems designed above, and avoid global or static
+In order to "fix" the problems exposed above, and avoid global or static
 scope pollution, two approaches are possible:
 
  - using a [`Closure`](http://php.net/manual/en/functions.anonymous.php), combined 

diff --git a/README.md b/README.md
@@ -0,0 +1,36 @@
+# `__invoke` VS `function` VS `Closure`
+
+This gist is about:
+
+ - https://twitter.com/taylorotwell/status/600680897550098432
+ - https://twitter.com/Ocramius/status/600705252539691008
+
+Mainly:
+
+ - `function` cannot (should not) be used when side-effects occur
+ - `function` does not work with dependency injection
+ - `function` is not testable in insulation if it isn't a pure function 
+   without dependencies
+
+In order to "fix" the problems designed above, and avoid global or static
+scope pollution, two approaches are possible:
+
+ - using a [`Closure`](http://php.net/manual/en/functions.anonymous.php), combined 
+   with a [higher order function](http://en.wikipedia.org/wiki/Higher-order_function) (also called **functor**)
+ - using an `object` that implements the [`__invoke`](http://php.net/manual/en/language.oop5.magic.php#object.invoke)
+   magic method
+
+Few notes:
+
+ - a class that only implements `__invoke` and `__construct` is basically 
+   a `function` combined with a `functor`
+ - a class can be easily tested in insulation
+ - a `Closure` with dependencies cannot be tested in insulation
+ - in order to make a `Closure` testable in insulation, it must be combined 
+   with a **higher order function**
+ - there is no runtime difference between using a `Closure` and any object
+   with an `__invoke` method defined in its class
+
+Therefore, `object` + `__invoke` is much simpler and flexible than using 
+a `Closure`, whereas a `function` is not applicable in any context that 
+requires the usage of [DI](http://en.wikipedia.org/wiki/Dependency_injection).
diff --git a/closure.php b/closure.php
@@ -0,0 +1,20 @@
+<?php
+
+// higher order function / factory - you name it
+$loginFactory = function (SessionRepository $sessions) {
+
+    return function (User $user) use ($sessions) {
+        // argh! (note that a static registry/locator isn't any better)
+        global $sessions;
+
+        $session = new Session($user);
+
+        $sessions->add($session);
+
+        return $session;
+    };
+};
+
+// usage (PHP 7) - see http://3v4l.org/kPnLM:
+
+$loginFactory(sessionRepository)($user);
diff --git a/function.php b/function.php
@@ -0,0 +1,17 @@
+<?php
+
+function login(User $user)
+{
+    // argh! (note that a static registry/locator isn't any better)
+    global $sessions;
+
+    $session = new Session($user);
+
+    $sessions->add($session);
+
+    return $session;
+}
+
+// usage:
+
+login($user);
diff --git a/__invoke.php b/__invoke.php
@@ -0,0 +1,26 @@
+<?php
+
+final class Login
+{
+    private $sessions;
+
+    public function __construct(SessionRepository $sessions)
+    {
+        $this->sessions = $sessions;
+    }
+
+    public function __invoke(User $user)
+    {
+        $session = new Session($user);
+
+        $this->sessions->add($session);
+
+        return $session;
+    }
+}
+
+// usage:
+
+$login = new Login($sessionRepository);
+
+$login($user);
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