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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23 | final class UnixDisk implements Disk |
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24 | { |
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25 | private static $columns = [ |
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26 | 'Size' => 'size', |
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27 | 'Used' => 'used', |
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28 | 'Avail' => 'available', |
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29 | 'Use%' => 'usage', |
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30 | 'Capacity' => 'usage', |
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31 | 'Mounted' => 'mountPoint', |
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32 | ]; |
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33 | |||
34 | /** |
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35 | * {@inheritdoc} |
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36 | */ |
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37 | 2 | public function volumes(): MapInterface |
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43 | |||
44 | 1 | public function get(MountPoint $point): Volume |
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50 | |||
51 | 2 | View Code Duplication | private function run(string $command): Str |
62 | |||
63 | /** |
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64 | * @return MapInterface<string, Volume> |
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1 ignored issue
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65 | */ |
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66 | 2 | private function parse(Str $output): MapInterface |
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122 | } |
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123 |
Let’s assume that you have a directory layout like this:
and let’s assume the following content of
Bar.php
:If both files
OtherDir/Foo.php
andSomeDir/Foo.php
are loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.php
However, as
OtherDir/Foo.php
does not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php
, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: