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 | /** |
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53 | * Flag to check whether meta function called by WP filter or directly |
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54 | * |
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55 | * @since 2.0 |
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56 | * @access protected |
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57 | */ |
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58 | private $is_filter_callback = false; |
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59 | |||
60 | |||
61 | /** |
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62 | * Meta supports. |
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63 | * |
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64 | * @since 2.0 |
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65 | * @access protected |
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66 | * @var array |
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67 | */ |
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68 | protected $supports = array( |
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69 | 'add_post_metadata', |
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70 | 'get_post_metadata', |
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71 | 'update_post_metadata', |
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72 | 'delete_post_metadata', |
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73 | 'posts_where', |
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74 | 'posts_join', |
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75 | 'posts_groupby', |
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76 | 'posts_orderby', |
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77 | ); |
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78 | |||
79 | /** |
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80 | * Give_DB_Meta constructor. |
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81 | * |
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82 | * @since 2.0 |
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83 | */ |
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84 | function __construct() { |
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124 | |||
125 | |||
126 | /** |
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127 | * Retrieve payment meta field for a payment. |
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128 | * |
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129 | * @access public |
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130 | * @since 2.0 |
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131 | * |
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132 | * @param int $id Pst Type ID. |
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133 | * @param string $meta_key The meta key to retrieve. |
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134 | * @param bool $single Whether to return a single value. |
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135 | * |
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136 | * @return mixed Will be an array if $single is false. Will be value of meta data field if $single |
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137 | * is true. |
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138 | */ |
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139 | public function get_meta( $id = 0, $meta_key = '', $single = false ) { |
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167 | |||
168 | |||
169 | /** |
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170 | * Add meta data field to a payment. |
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171 | * |
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172 | * For internal use only. Use Give_Payment->add_meta() for public usage. |
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173 | * |
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174 | * @access private |
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175 | * @since 2.0 |
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176 | * |
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177 | * @param int $id Post Type ID. |
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178 | * @param string $meta_key Metadata name. |
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179 | * @param mixed $meta_value Metadata value. |
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180 | * @param bool $unique Optional, default is false. Whether the same key should not be added. |
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181 | * |
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182 | * @return int|bool False for failure. True for success. |
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183 | */ |
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184 | public function add_meta( $id, $meta_key, $meta_value, $unique = false ) { |
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204 | |||
205 | /** |
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206 | * Update payment meta field based on Post Type ID. |
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207 | * |
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208 | * For internal use only. Use Give_Payment->update_meta() for public usage. |
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209 | * |
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210 | * Use the $prev_value parameter to differentiate between meta fields with the |
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211 | * same key and Post Type ID. |
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212 | * |
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213 | * If the meta field for the payment does not exist, it will be added. |
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214 | * |
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215 | * @access public |
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216 | * @since 2.0 |
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217 | * |
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218 | * @param int $id Post Type ID. |
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219 | * @param string $meta_key Metadata key. |
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220 | * @param mixed $meta_value Metadata value. |
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221 | * @param mixed $prev_value Optional. Previous value to check before removing. |
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222 | * |
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223 | * @return int|bool False on failure, true if success. |
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224 | */ |
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225 | View Code Duplication | public function update_meta( $id, $meta_key, $meta_value, $prev_value = '' ) { |
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245 | |||
246 | /** |
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247 | * Remove metadata matching criteria from a payment. |
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248 | * |
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249 | * You can match based on the key, or key and value. Removing based on key and |
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250 | * value, will keep from removing duplicate metadata with the same key. It also |
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251 | * allows removing all metadata matching key, if needed. |
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252 | * |
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253 | * @access public |
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254 | * @since 2.0 |
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255 | * |
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256 | * @param int $id Post Type ID. |
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257 | * @param string $meta_key Metadata name. |
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258 | * @param mixed $meta_value Optional. Metadata value. |
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259 | * @param mixed $delete_all Optional. |
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260 | * |
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261 | * @return bool False for failure. True for success. |
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262 | */ |
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263 | View Code Duplication | public function delete_meta( $id = 0, $meta_key = '', $meta_value = '', $delete_all = '' ) { |
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284 | |||
285 | /** |
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286 | * Rename query clauses of every query for new meta table |
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287 | * |
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288 | * @since 2.0 |
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289 | * @access public |
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290 | * |
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291 | * @param string $clause |
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292 | * @param WP_Query $wp_query |
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293 | * |
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294 | * @return string |
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295 | */ |
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296 | public function __rename_meta_table_name_in_query( $clause, $wp_query ) { |
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304 | |||
305 | |||
306 | /** |
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307 | * Rename query clauses for new meta table |
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308 | * |
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309 | * @param $clause |
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310 | * @param $filter |
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311 | * |
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312 | * @return mixed |
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313 | */ |
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314 | public function __rename_meta_table_name( $clause, $filter ) { |
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355 | |||
356 | |||
357 | /** |
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358 | * Check if current query for post type or not. |
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359 | * |
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360 | * @since 2.0 |
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361 | * @access protected |
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362 | * |
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363 | * @param WP_Query $wp_query |
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364 | * |
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365 | * @return bool |
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366 | */ |
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367 | protected function is_post_type_query( $wp_query ) { |
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388 | |||
389 | /** |
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390 | * Check if current id of post type or not |
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391 | * |
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392 | * @since 2.0 |
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393 | * @access protected |
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394 | * |
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395 | * @param $ID |
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396 | * |
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397 | * @return bool |
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398 | */ |
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399 | protected function is_valid_post_type( $ID ) { |
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402 | |||
403 | /** |
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404 | * check if custom meta table enabled or not. |
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405 | * |
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406 | * @since 2.0 |
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407 | * @access protected |
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408 | * @return bool |
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409 | */ |
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410 | protected function is_custom_meta_table_active() { |
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413 | |||
414 | |||
415 | /** |
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416 | * Update last_changed key |
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417 | * |
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418 | * @since 2.0 |
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419 | * @access private |
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420 | * |
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421 | * @param int $id |
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422 | * @param string $meta_type |
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423 | * |
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424 | * @return void |
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425 | */ |
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426 | private function delete_cache( $id, $meta_type = '' ) { |
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441 | |||
442 | /** |
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443 | * Add support for hidden functions. |
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444 | * |
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445 | * @since 2.0 |
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446 | * @access public |
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447 | * |
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448 | * @param $name |
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449 | * @param $arguments |
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450 | * |
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451 | * @return mixed |
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452 | */ |
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453 | public function __call( $name, $arguments ) { |
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516 | |||
517 | /** |
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518 | * Create Meta Tables. |
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519 | * |
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520 | * @since 2.0.1 |
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521 | * @access public |
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522 | */ |
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523 | public function create_table() { |
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543 | |||
544 | |||
545 | /** |
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546 | * Get meta type |
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547 | * |
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548 | * @since 2.0.4 |
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549 | * @access public |
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550 | * |
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551 | * @return string |
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552 | */ |
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553 | public function get_meta_type() { |
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556 | |||
557 | /** |
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558 | * Remove all meta data matching criteria from a meta table. |
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559 | * |
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560 | * @since 2.1.3 |
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561 | * @access public |
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562 | * |
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563 | * @param int $id ID. |
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564 | * |
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565 | * @return bool False for failure. True for success. |
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566 | */ |
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567 | public function delete_all_meta( $id = 0 ) { |
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577 | } |
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578 |
Adding explicit visibility (
private
,protected
, orpublic
) is generally recommend to communicate to other developers how, and from where this method is intended to be used.