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41 lines
1.3 KiB
PHP
41 lines
1.3 KiB
PHP
<?php
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/*
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* DesignPatternPHP
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*/
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namespace DesignPatterns\NullObject;
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/**
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* NullOutput is a example of NullObject pattern. It is not formely a Design
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* Pattern by the GoF but it's a schema which appears frequently enough to
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* be a pattern. Futhermore it is a really good pattern in my opinion :
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* - the code in the client is simple
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* - it reduces the chance of null pointer exception
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* - less "if" => less test cases
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*
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* The purpose : every time you have a method which returns an object or null,
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* you should return an object or a "NullObject". With NullObject, you don't need
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* statement like "if (!is_null($obj)) { $obj->callSomething(); }" anymore.
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*
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* In this case, this a logger which does nothing. Other examples :
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* - null logger of symfony profiler
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* - null output in symfony/console
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* - null handler in a Chain of Responsiblities pattern
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* - null command in a Command pattern
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*
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* Performance concerns : ok there is a call for nothing but we spare an "if is_null"
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* I didn't run a benchmark but I think it's equivalent.
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*
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* Key feature : of course this logger MUST implement the same interface (or abstract)
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* like the other loggers.
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*/
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class NullLogger implements LoggerInterface
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{
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public function log($str)
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{
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// do nothing
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}
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} |