Updated README.md

Author: marc-mabe

README.md

@@ -1,12 +1,26 @@
 # php-enum [![Build Status](https://secure.travis-ci.org/marc-mabe/php-enum.png?branch=master)](http://travis-ci.org/marc-mabe/php-enum)
 
-This is a native PHP implementation to add enumarable support to PHP.
-It's an abstract class that can be extended to emulate enumerables.
+This is a native PHP implementation to add enumeration support to PHP 5.x.
+It's an abstract class that needs to be extended to use it.
+
+
+# What is an Enumeration?
+
+[Wikipedia](http://wikipedia.org/wiki/Enumerated_type)
+> In computer programming, an enumerated type (also called enumeration or enum)
+> is a data type consisting of a set of named values called elements, members
+> or enumerators of the type. The enumerator names are usually identifiers that
+> behave as constants in the language. A variable that has been declared as
+> having an enumerated type can be assigned any of the enumerators as a value.
+> In other words, an enumerated type has values that are different from each
+> other, and that can be compared and assigned, but which do not have any
+> particular concrete representation in the computer's memory; compilers and
+> interpreters can represent them arbitrarily.
 
 
 # Why not ```SplEnum```
 
-* It's not build-in PHP and requires pecl/extension
+* It's not build-in PHP and requires pecl extension
 * SplEnum is too much magic under the hod
 * SplEnum hasn't strict comparison
 
@@ -26,47 +40,15 @@ It's an abstract class that can be extended to emulate enumerables.
         final public function __invoke();   // Alias of getValue()
     }
 
-## Examples:
-
-    // Enum with ONE as default value
-    class MyEnumWithDefaultValue extends Mabe_Enum
-    {
-        const ONE = 1;
-        const TWO = 2;
-        protected $value = 1;
-    }
-
-    // Enum without a default value
-    // No argument on constructor results in InvalidArgumentException
-    class MyEnumWithoutDefaultValue extends Mabe_Enum
-    {
-        const ONE = 1;
-        const TWO = 2;
-    }
 
-    // Because the $value object property is defined as NULL
-    // a constant with a NULL value gets the default value automatically
-    class MyEnumWithNullAsDefaultValue extends Mabe_Enum
-    {
-        const NONE = null;
-        const ONE  = 1;
-        const TWO  = 2;
-    }
-
-    // To disable the last behavior it's possible to set the default value to an unknown value
-    class MyEnumWithoutNullAsDefaultValue extends Mabe_Enum
-    {
-        const NONE = null;
-        const ONE  = 1;
-        const TWO  = 2;
-        protected $value = -1;
-    }
-
-
-# Class constants vs. php-enum
+# Usage
 
 ## The way of class constants
 
+* Requires validation on every use
+* Hard to extend the list of possible values
+* Hard to get a human readable name of a value
+
     class User
     {
         const INACTIVE = 0;
@@ -95,16 +77,17 @@ It's an abstract class that can be extended to emulate enumerables.
     $user->setStatus(User::ACTIVE);
     echo 'Changed user status: ' . $user->getStatus() . PHP_EOL;
 
-    PRINTS:
+**PRINTS**
+
     Default user status: 0
     Changed user status: 1
 
-* Requires validation on every use
-* Hard to extend the list of possible values
-* Hard to get a human readable name of a value
-
 ## The way of php-enum:
 
+* Validation will be already done on basic class ```Mabe_Enum```
+* Using type-hint makes arguments save
+* Human readable name of a value is simple accessable
+
     class UserStatusEnum extends Mabe_Enum
     {
         const INACTIVE = 0;
@@ -123,7 +106,7 @@ It's an abstract class that can be extended to emulate enumerables.
         {
             $this->status = $status;
         }
- 
+
         public function getStatus()
         {
             if (!$this->status) {
@@ -139,13 +122,83 @@ It's an abstract class that can be extended to emulate enumerables.
     $user->setStatus(new UserStatusEnum(UserStatusEnum::ACTIVE));
     echo 'Changed user status: ' . $user->getStatus() . '(' . $user->getStatus()->getValue() . ')' . PHP_EOL;
 
-    PRINTS:
+**PRINTS**
+
     Default user status: INACTIVE (0)
     Changed user status: ACTIVE (1)
 
-* Validation already done on basic class ```Mabe_Enum```
-* Using type-hint makes arguments save
-* Human readable name of a value is simple accessable
+
+# Installation
+
+## Composer
+
+Add ```marc-mabe/php-enum``` to the project's composer.json dependencies and run
+```php composer.phar install```
+
+## GIT
+
+```git clone git://github.com/marc-mabe/php-enum.git```
+(The class ```Mabe_Enum``` will be located in ```src/Mabe/Enum.php```)
+
+## ZIP / TAR
+
+Download the last version from [Github](https://github.com/marc-mabe/php-enum/tags)
+and extract it.
+(The class ```Mabe_Enum``` will be located in ```src/Mabe/Enum.php```)
+
+
+# Examples
+
+## Define a default value:
+
+This example defines the constant ```ONE``` with value ```1``` as default
+value.
+
+    class MyEnumWithDefaultValue extends Mabe_Enum
+    {
+        const ONE = 1;
+        const TWO = 2;
+        protected $value = 1;
+    }
+
+## Enum without a default value
+
+Don't define a ```$value``` to not define a default value if none of your
+constant values has ```NULL``` as value.
+
+That's because ```$value``` was defined as ```NULL``` in the base class and
+No constant assignable to the default value.
+
+* No argument on constructor results in an InvalidArgumentException
+
+    class MyEnumWithoutDefaultValue extends Mabe_Enum
+    {
+        const ONE = 1;
+        const TWO = 2;
+    }
+
+## Constant with NULL as value
+
+Because ```$value``` property is defined as ```NULL``` a constant with
+```NULL```  as value gets the default value automatically.
+
+    class MyEnumWithNullAsDefaultValue extends Mabe_Enum
+    {
+        const NONE = null;
+        const ONE  = 1;
+        const TWO  = 2;
+    }
+
+To disable this behavior simply define ```$value``` to a value not assignable
+to a constant.
+
+    class MyEnumWithoutNullAsDefaultValue extends Mabe_Enum
+    {
+        const NONE = null;
+        const ONE  = 1;
+        const TWO  = 2;
+        protected $value = -1;
+    }
 
 
 # New BSD License