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:
Complex classes like Give_DB_Meta 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 Give_DB_Meta, and based on these observations, apply Extract Interface, too.
1 | <?php |
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17 | class Give_DB_Meta extends Give_DB { |
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18 | /** |
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19 | * Post type |
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20 | * |
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21 | * @since 2.0 |
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22 | * @access protected |
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23 | * @var bool |
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24 | */ |
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25 | protected $post_type = ''; |
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26 | |||
27 | /** |
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28 | * Meta type |
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29 | * |
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30 | * @since 2.0 |
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31 | * @access protected |
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32 | * @var bool |
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33 | */ |
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34 | protected $meta_type = ''; |
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35 | |||
36 | /** |
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37 | * Flag to handle result type |
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38 | * |
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39 | * @since 2.0 |
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40 | * @access protected |
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41 | */ |
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42 | protected $raw_result = false; |
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43 | |||
44 | /** |
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45 | * Flag for short circuit of meta function |
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46 | * |
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47 | * @since 2.0 |
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48 | * @access protected |
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49 | */ |
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50 | protected $check = false; |
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51 | |||
52 | |||
53 | /** |
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54 | * Meta supports. |
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55 | * |
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56 | * @since 2.0 |
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57 | * @access protected |
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58 | * @var array |
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59 | */ |
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60 | protected $supports = array( |
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61 | 'add_post_metadata', |
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62 | 'get_post_metadata', |
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63 | 'update_post_metadata', |
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64 | 'delete_post_metadata', |
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65 | 'posts_where', |
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66 | 'posts_join', |
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67 | 'posts_groupby', |
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68 | 'posts_orderby' |
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69 | ); |
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70 | |||
71 | /** |
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72 | * Give_DB_Meta constructor. |
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73 | * |
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74 | * @since 2.0 |
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75 | */ |
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76 | function __construct() { |
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114 | |||
115 | |||
116 | /** |
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117 | * Retrieve payment meta field for a payment. |
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118 | * |
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119 | * @access public |
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120 | * @since 2.0 |
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121 | * |
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122 | * @param int $id Pst Type ID. |
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123 | * @param string $meta_key The meta key to retrieve. |
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124 | * @param bool $single Whether to return a single value. |
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125 | * |
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126 | * @return mixed Will be an array if $single is false. Will be value of meta data field if $single |
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127 | * is true. |
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128 | */ |
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129 | public function get_meta( $id = 0, $meta_key = '', $single = false ) { |
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151 | |||
152 | |||
153 | /** |
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154 | * Add meta data field to a payment. |
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155 | * |
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156 | * For internal use only. Use Give_Payment->add_meta() for public usage. |
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157 | * |
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158 | * @access private |
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159 | * @since 2.0 |
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160 | * |
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161 | * @param int $id Post Type ID. |
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162 | * @param string $meta_key Metadata name. |
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163 | * @param mixed $meta_value Metadata value. |
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164 | * @param bool $unique Optional, default is false. Whether the same key should not be added. |
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165 | * |
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166 | * @return int|bool False for failure. True for success. |
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167 | */ |
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168 | View Code Duplication | public function add_meta( $id = 0, $meta_key = '', $meta_value, $unique = false ) { |
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184 | |||
185 | /** |
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186 | * Update payment meta field based on Post Type ID. |
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187 | * |
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188 | * For internal use only. Use Give_Payment->update_meta() for public usage. |
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189 | * |
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190 | * Use the $prev_value parameter to differentiate between meta fields with the |
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191 | * same key and Post Type ID. |
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192 | * |
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193 | * If the meta field for the payment does not exist, it will be added. |
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194 | * |
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195 | * @access public |
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196 | * @since 2.0 |
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197 | * |
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198 | * @param int $id Post Type ID. |
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199 | * @param string $meta_key Metadata key. |
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200 | * @param mixed $meta_value Metadata value. |
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201 | * @param mixed $prev_value Optional. Previous value to check before removing. |
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202 | * |
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203 | * @return int|bool False on failure, true if success. |
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204 | */ |
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205 | View Code Duplication | public function update_meta( $id = 0, $meta_key = '', $meta_value, $prev_value = '' ) { |
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221 | |||
222 | /** |
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223 | * Remove metadata matching criteria from a payment. |
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224 | * |
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225 | * You can match based on the key, or key and value. Removing based on key and |
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226 | * value, will keep from removing duplicate metadata with the same key. It also |
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227 | * allows removing all metadata matching key, if needed. |
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228 | * |
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229 | * @access public |
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230 | * @since 2.0 |
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231 | * |
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232 | * @param int $id Post Type ID. |
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233 | * @param string $meta_key Metadata name. |
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234 | * @param mixed $meta_value Optional. Metadata value. |
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235 | * @param mixed $delete_all Optional. |
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236 | * |
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237 | * @return bool False for failure. True for success. |
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238 | */ |
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239 | View Code Duplication | public function delete_meta( $id = 0, $meta_key = '', $meta_value = '', $delete_all = '' ) { |
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255 | |||
256 | /** |
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257 | * Rename query clauses of every query for new meta table |
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258 | * |
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259 | * @since 2.0 |
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260 | * @access public |
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261 | * |
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262 | * @param string $clause |
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263 | * @param WP_Query $wp_query |
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264 | * |
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265 | * @return string |
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266 | */ |
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267 | public function __rename_meta_table_name_in_query( $clause, $wp_query ) { |
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308 | |||
309 | |||
310 | /** |
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311 | * Check if current query for post type or not. |
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312 | * |
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313 | * @since 2.0 |
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314 | * @access protected |
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315 | * |
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316 | * @param WP_Query $wp_query |
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317 | * |
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318 | * @return bool |
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319 | */ |
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320 | protected function is_post_type_query( $wp_query ) { |
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340 | |||
341 | /** |
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342 | * Check if current id of post type or not |
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343 | * |
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344 | * @since 2.0 |
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345 | * @access protected |
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346 | * |
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347 | * @param $ID |
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348 | * |
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349 | * @return bool |
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350 | */ |
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351 | protected function is_valid_post_type( $ID ) { |
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354 | |||
355 | /** |
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356 | * check if custom meta table enabled or not. |
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357 | * |
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358 | * @since 2.0 |
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359 | * @access protected |
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360 | * @return bool |
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361 | */ |
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362 | protected function is_custom_meta_table_active() { |
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365 | |||
366 | |||
367 | /** |
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368 | * Update last_changed key |
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369 | * |
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370 | * @since 2.0 |
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371 | * @access private |
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372 | * |
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373 | * @param int $id |
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374 | * @param string $meta_type |
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375 | * |
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376 | * @return void |
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377 | */ |
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378 | private function delete_cache( $id, $meta_type = '' ) { |
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393 | |||
394 | /** |
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395 | * Add support for hidden functions. |
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396 | * |
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397 | * @since 2.0 |
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398 | * @access public |
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399 | * |
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400 | * @param $name |
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401 | * @param $arguments |
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402 | * |
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403 | * @return mixed |
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404 | */ |
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405 | public function __call( $name, $arguments ) { |
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464 | } |