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Bilge
2014-10-06 02:16:35 +01:00
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Behavioral/NullObject/README.md
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## Purpose
NullOutput is a example of NullObject pattern. It is not formally a Design Pattern by the GoF but it's a schema which appears frequently enough to
be a pattern. Furthermore it is a really good pattern in my opinion:
NullObject is not a GoF design pattern but a schema which appears frequently enough to be considered a pattern. It has the following benefits:
* the code in the client is simple
* it reduces the chance of null pointer exception
* less "if" => less test cases
* Client code is simplified
* Reduces the chance of null pointer exceptions
* Fewer conditionals require less test cases
Every time you have a method which returns an object or null, you should return an object or a `NullObject`. With NullObject, you don't need
a statement like `if (!is_null($obj)) { $obj->callSomething(); }` anymore.
Methods that return an object or null should instead return an object or `NullObject`. `NullObject`s simplify boilerplate code such as `if (!is_null($obj)) { $obj->callSomething(); }` to just `$obj->callSomething();` by eliminating the conditional check in client code.
## Examples
@ -21,4 +19,4 @@ a statement like `if (!is_null($obj)) { $obj->callSomething(); }` anymore.
## UML Diagram
![Alt NullObject UML Diagram](uml/uml.png)
![Alt NullObject UML Diagram](uml/uml.png)