[Console] Command Lifecycle explications

Author: 94noni

components/console/introduction.rst

@@ -110,6 +110,31 @@ This prints::
 
     HELLO FABIEN
 
+Command Lifecycle
+~~~~~~~~~~~~~~~~~
+
+Commands have three lifecycle methods:
+
+:method:`Symfony\\Component\\Console\\Command\\Command::initialize`
+    This method is executed before the ``interact()`` and the ``execute()``
+    methods. It's main purpose is to initialize the variables used in the
+    rest of the command methods.
+
+:method:`Symfony\\Component\\Console\\Command\\Command::interact`
+    This method is executed after ``initialize()`` and before ``execute()``.
+    Its purpose is to check if some of the options/arguments are missing
+    and interactively ask the user for those values. This is the last place
+    where you can ask for missing options/arguments otherwise the command
+    will throw an error.
+
+:method:`Symfony\\Component\\Console\\Command\\Command::execute`
+    This method is executed after ``interact()`` and ``initialize()``.
+    It contains the logic you want the command executes.
+
+Note that ``execute()`` is the only required method of the three.
+
+The ``initialize()`` and ``interact()`` methods are completely optional.
+
 .. _components-console-coloring:
 
 Coloring the Output