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1 | <?php |
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2 | |||
3 | namespace SRF\Formats\Tree; |
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4 | |||
5 | use Cdb\Exception; |
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6 | use Tree\Node\Node; |
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7 | use Tree\Node\NodeInterface; |
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8 | use Tree\Node\NodeTrait; |
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9 | |||
10 | class TreeNode extends Node { |
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11 | |||
12 | /** |
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13 | * SRFTreeElement constructor. |
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14 | * |
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15 | * @param \SMWResultArray[] | null $row |
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16 | */ |
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17 | 5 | public function __construct( $row = null ) { |
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18 | 5 | parent::__construct( $row ); |
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19 | 5 | } |
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20 | |||
21 | /** |
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22 | * @return string |
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23 | */ |
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24 | 5 | public function getHash() { |
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25 | |||
26 | 5 | $resultSubject = $this->getResultSubject(); |
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27 | |||
28 | 5 | if ( $resultSubject !== null ) { |
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29 | 5 | return $resultSubject->getSerialization(); |
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30 | } |
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31 | |||
32 | 5 | return ''; |
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33 | } |
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34 | |||
35 | /** |
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36 | * @return null|\SMWDIWikiPage |
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37 | */ |
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38 | 5 | public function getResultSubject() { |
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39 | /** @var \SMWResultArray[] | null $row */ |
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40 | 5 | $row = $this->getValue(); |
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41 | |||
42 | 5 | if ( $row !== null ) { |
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43 | 5 | return $row[0]->getResultSubject(); |
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44 | } |
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45 | |||
46 | 5 | return null; |
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47 | } |
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48 | |||
49 | /** |
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50 | * @param NodeInterface $child |
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51 | * |
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52 | * @return NodeTrait |
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53 | * @throws Exception |
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54 | */ |
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55 | 5 | public function addChild( NodeInterface $child ) { |
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56 | |||
57 | 5 | foreach ( $this->getAncestorsAndSelf() as $ancestor ) { |
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58 | 5 | if ( $ancestor->getHash() === $child->getHash() ) { |
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0 ignored issues
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59 | 5 | throw new Exception( 'srf-tree-circledetected' ); |
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60 | } |
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61 | } |
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62 | |||
63 | 5 | return parent::addChild( $child ); |
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0 ignored issues
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show
The return type of
return parent::addChild($child); (SRF\Formats\Tree\TreeNode ) is incompatible with the return type of the parent method Tree\Node\Node::addChild of type Tree\Node\NodeTrait .
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design. Let’s take a look at an example: class Author {
private $name;
public function __construct($name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
}
abstract class Post {
public function getAuthor() {
return 'Johannes';
}
}
class BlogPost extends Post {
public function getAuthor() {
return new Author('Johannes');
}
}
class ForumPost extends Post { /* ... */ }
function my_function(Post $post) {
echo strtoupper($post->getAuthor());
}
Our function
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64 | } |
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65 | |||
66 | } |
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67 | |||
68 |
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: