Complex classes like DbConnection often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use DbConnection, and based on these observations, apply Extract Interface, too.
1 | <?php /** MicroDataBaseConnection */ |
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19 | class DbConnection extends Connection |
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20 | { |
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21 | /** @var \PDO|null $conn Connection to DB */ |
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22 | protected $conn; |
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23 | |||
24 | |||
25 | /** |
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26 | * Construct for this class |
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27 | * |
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28 | * @access public |
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29 | * |
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30 | * @param array $config configuration array |
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31 | * |
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32 | * @result void |
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33 | * @throws Exception |
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34 | */ |
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35 | public function __construct(array $config = []) |
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56 | |||
57 | /** |
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58 | * Destructor for this class |
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59 | * |
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60 | * @access public |
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61 | * @return void |
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62 | */ |
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63 | public function __destruct() |
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67 | |||
68 | /** |
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69 | * @inheritdoc |
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70 | */ |
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71 | public function rawQuery($query = '', array $params = [], $fetchType = \PDO::FETCH_ASSOC, $fetchClass = 'Model') |
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90 | |||
91 | /** |
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92 | * @inheritdoc |
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93 | */ |
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94 | public function listDatabases() |
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105 | |||
106 | /** |
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107 | * @inheritdoc |
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108 | */ |
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109 | public function infoDatabase($dbName) |
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127 | |||
128 | /** |
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129 | * @inheritdoc |
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130 | */ |
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131 | public function tableExists($table) |
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135 | |||
136 | /** |
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137 | * @inheritdoc |
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138 | */ |
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139 | public function listTables() |
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143 | |||
144 | /** |
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145 | * @inheritdoc |
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146 | */ |
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147 | public function createTable($name, array $elements = [], $params = '') |
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153 | |||
154 | /** |
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155 | * @inheritdoc |
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156 | */ |
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157 | public function clearTable($name) |
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161 | |||
162 | /** |
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163 | * @inheritdoc |
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164 | */ |
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165 | public function removeTable($name) |
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169 | |||
170 | /** |
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171 | * @inheritdoc |
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172 | */ |
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173 | public function fieldExists($field, $table) |
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183 | |||
184 | /** |
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185 | * @inheritdoc |
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186 | */ |
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187 | public function listFields($table) |
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205 | |||
206 | /** |
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207 | * @inheritdoc |
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208 | */ |
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209 | public function fieldInfo($field, $table) |
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215 | |||
216 | /** |
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217 | * @inheritdoc |
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218 | */ |
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219 | public function switchDatabase($dbName) |
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227 | |||
228 | /** |
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229 | * @inheritdoc |
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230 | */ |
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231 | public function insert($table, array $line = [], $multi = false) |
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256 | |||
257 | /** |
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258 | * @inheritdoc |
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259 | */ |
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260 | public function update($table, array $elements = [], $conditions = '') |
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281 | |||
282 | /** |
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283 | * @inheritdoc |
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284 | */ |
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285 | public function delete($table, $conditions, array $ph = []) |
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291 | |||
292 | /** |
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293 | * @inheritdoc |
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294 | */ |
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295 | public function exists($table, array $params = []) |
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309 | |||
310 | /** |
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311 | * @inheritdoc |
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312 | */ |
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313 | public function count($subQuery = '', $table = '') |
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328 | } |
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329 |
This check looks for variable assignements that are either overwritten by other assignments or where the variable is not used subsequently.
Both the
$myVar
assignment in line 1 and the$higher
assignment in line 2 are dead. The first because$myVar
is never used and the second because$higher
is always overwritten for every possible time line.