Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
| 1 | <?php  | 
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| 8 | class CategoryController extends Controller  | 
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| 9 | { | 
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| 10 | |||
| 11 | public function __construct()  | 
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| 17 | |||
| 18 | /**  | 
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| 19 | * Show the article by his id.  | 
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| 20 | *  | 
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| 21 | * @return \Illuminate\Http\RedirectResponse|\Illuminate\View\View  | 
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| 22 | */  | 
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| 23 | View Code Duplication | public function show(Request $request, $slug, $id)  | 
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| 50 | }  | 
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| 51 | 
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: