To write code that is easy readable just like sentences in a natural language (like English).

• Doctrine2's QueryBuilder works something like that example class below
• PHPUnit uses fluent interfaces to build mock objects

You can also find this code on GitHub

Sql.php

.. literalinclude:: Sql.php
   :language: php
   :linenos:

Tests/FluentInterfaceTest.php

.. literalinclude:: Tests/FluentInterfaceTest.php
   :language: php
   :linenos: