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 WC_Shipping_Method 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 WC_Shipping_Method, and based on these observations, apply Extract Interface, too.
1 | <?php |
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18 | abstract class WC_Shipping_Method extends WC_Settings_API { |
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19 | |||
20 | /** |
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21 | * Features this method supports. Possible features used by core: |
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22 | * - shipping-zones Shipping zone functionality + instances |
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23 | * - instance-settings Instance settings screens. |
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24 | * - settings Non-instance settings screens. Enabled by default for BW compatibility with methods before instances existed. |
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25 | * - instance-settings-modal Allows the instance settings to be loaded within a modal in the zones UI. |
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26 | * @var array |
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27 | */ |
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28 | public $supports = array( 'settings' ); |
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29 | |||
30 | /** |
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31 | * Unique ID for the shipping method - must be set. |
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32 | * @var string |
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33 | */ |
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34 | public $id = ''; |
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35 | |||
36 | /** |
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37 | * Method title. |
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38 | * @var string |
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39 | */ |
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40 | public $method_title = ''; |
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41 | |||
42 | /** |
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43 | * Method description. |
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44 | * @var string |
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45 | */ |
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46 | public $method_description = ''; |
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47 | |||
48 | /** |
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49 | * yes or no based on whether the method is enabled. |
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50 | * @var string |
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51 | */ |
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52 | public $enabled = 'yes'; |
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53 | |||
54 | /** |
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55 | * Shipping method title for the frontend. |
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56 | * @var string |
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57 | */ |
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58 | public $title; |
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59 | |||
60 | /** |
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61 | * This is an array of rates - methods must populate this array to register shipping costs. |
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62 | * @var array |
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63 | */ |
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64 | public $rates = array(); |
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65 | |||
66 | /** |
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67 | * If 'taxable' tax will be charged for this method (if applicable). |
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68 | * @var string |
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69 | */ |
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70 | public $tax_status = 'taxable'; |
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71 | |||
72 | /** |
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73 | * Fee for the method (if applicable). |
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74 | * @var string |
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75 | */ |
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76 | public $fee = null; |
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77 | |||
78 | /** |
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79 | * Minimum fee for the method (if applicable). |
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80 | * @var string |
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81 | */ |
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82 | public $minimum_fee = null; |
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83 | |||
84 | /** |
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85 | * Instance ID if used. |
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86 | * @var int |
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87 | */ |
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88 | public $instance_id = 0; |
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89 | |||
90 | /** |
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91 | * Instance form fields. |
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92 | * @var array |
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93 | */ |
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94 | public $instance_form_fields = array(); |
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95 | |||
96 | /** |
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97 | * Instance settings. |
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98 | * @var array |
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99 | */ |
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100 | public $instance_settings = array(); |
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101 | |||
102 | /** |
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103 | * Availability - legacy. Used for method Availability. |
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104 | * No longer useful for instance based shipping methods. |
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105 | * @deprecated 2.6.0 |
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106 | * @var string |
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107 | */ |
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108 | public $availability; |
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109 | |||
110 | /** |
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111 | * Availability countries - legacy. Used for method Availability. |
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112 | * No longer useful for instance based shipping methods. |
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113 | * @deprecated 2.6.0 |
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114 | * @var array |
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115 | */ |
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116 | public $countries = array(); |
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117 | |||
118 | /** |
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119 | * Constructor. |
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120 | * @param int $instance_id |
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121 | */ |
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122 | public function __construct( $instance_id = 0 ) { |
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125 | |||
126 | /** |
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127 | * Check if a shipping method supports a given feature. |
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128 | * |
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129 | * Methods should override this to declare support (or lack of support) for a feature. |
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130 | * |
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131 | * @param $feature string The name of a feature to test support for. |
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132 | * @return bool True if the shipping method supports the feature, false otherwise. |
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133 | */ |
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134 | public function supports( $feature ) { |
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137 | |||
138 | /** |
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139 | * Called to calculate shipping rates for this method. Rates can be added using the add_rate() method. |
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140 | */ |
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141 | public function calculate_shipping( $package = array() ) {} |
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142 | |||
143 | /** |
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144 | * Whether or not we need to calculate tax on top of the shipping rate. |
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145 | * @return boolean |
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146 | */ |
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147 | public function is_taxable() { |
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150 | |||
151 | /** |
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152 | * Whether or not this method is enabled in settings. |
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153 | * @since 2.6.0 |
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154 | * @return boolean |
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155 | */ |
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156 | public function is_enabled() { |
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159 | |||
160 | /** |
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161 | * Return the shipping method instance ID. |
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162 | * @since 2.6.0 |
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163 | * @return int |
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164 | */ |
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165 | public function get_instance_id() { |
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168 | |||
169 | /** |
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170 | * Return the shipping method title. |
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171 | * @since 2.6.0 |
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172 | * @return string |
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173 | */ |
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174 | public function get_method_title() { |
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177 | |||
178 | /** |
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179 | * Return the shipping method description. |
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180 | * @since 2.6.0 |
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181 | * @return string |
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182 | */ |
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183 | public function get_method_description() { |
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186 | |||
187 | /** |
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188 | * Return the shipping title which is user set. |
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189 | * |
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190 | * @return string |
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191 | */ |
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192 | public function get_title() { |
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195 | |||
196 | /** |
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197 | * Return calculated rates for a package. |
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198 | * @since 2.6.0 |
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199 | * @param object $package |
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200 | * @return array |
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201 | */ |
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202 | public function get_rates_for_package( $package ) { |
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209 | |||
210 | /** |
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211 | * Returns a rate ID based on this methods ID and instance, with an optional |
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212 | * suffix if distinguishing between multiple rates. |
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213 | * @since 2.6.0 |
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214 | * @param string $suffix |
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215 | * @return string |
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216 | */ |
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217 | public function get_rate_id( $suffix = '' ) { |
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230 | |||
231 | /** |
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232 | * Add a shipping rate. If taxes are not set they will be calculated based on cost. |
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233 | * @param array $args (default: array()) |
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234 | */ |
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235 | public function add_rate( $args = array() ) { |
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284 | |||
285 | /** |
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286 | * Calc taxes per item being shipping in costs array. |
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287 | * @since 2.6.0 |
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288 | * @access protected |
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289 | * @param array $costs |
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290 | * @return array of taxes |
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291 | */ |
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292 | protected function get_taxes_per_item( $costs ) { |
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326 | |||
327 | /** |
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328 | * Is this method available? |
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329 | * @param array $package |
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330 | * @return bool |
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331 | */ |
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332 | public function is_available( $package ) { |
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355 | |||
356 | /** |
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357 | * Get fee to add to shipping cost. |
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358 | * @param string|float $fee |
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359 | * @param float $total |
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360 | * @return float |
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361 | */ |
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362 | public function get_fee( $fee, $total ) { |
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371 | |||
372 | /** |
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373 | * Does this method have a settings page? |
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374 | * @return bool |
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375 | */ |
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376 | public function has_settings() { |
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379 | |||
380 | /** |
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381 | * Return admin options as a html string. |
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382 | * @return string |
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383 | */ |
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384 | public function get_admin_options_html() { |
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393 | |||
394 | /** |
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395 | * Output the shipping settings screen. |
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396 | */ |
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397 | public function admin_options() { |
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404 | |||
405 | /** |
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406 | * get_option function. |
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407 | * |
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408 | * Gets and option from the settings API, using defaults if necessary to prevent undefined notices. |
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409 | * |
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410 | * @param string $key |
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411 | * @param mixed $empty_value |
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412 | * @return mixed The value specified for the option or a default value for the option. |
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413 | */ |
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414 | public function get_option( $key, $empty_value = null ) { |
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423 | |||
424 | /** |
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425 | * Gets an option from the settings API, using defaults if necessary to prevent undefined notices. |
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426 | * |
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427 | * @param string $key |
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428 | * @param mixed $empty_value |
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429 | * @return mixed The value specified for the option or a default value for the option. |
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430 | */ |
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431 | View Code Duplication | public function get_instance_option( $key, $empty_value = null ) { |
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448 | |||
449 | /** |
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450 | * Get settings fields for instances of this shipping method (within zones). |
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451 | * Should be overridden by shipping methods to add options. |
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452 | * @since 2.6.0 |
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453 | * @return array |
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454 | */ |
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455 | public function get_instance_form_fields() { |
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458 | |||
459 | /** |
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460 | * Return the name of the option in the WP DB. |
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461 | * @since 2.6.0 |
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462 | * @return string |
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463 | */ |
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464 | public function get_instance_option_key() { |
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467 | |||
468 | /** |
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469 | * Initialise Settings for instances. |
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470 | * @since 2.6.0 |
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471 | */ |
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472 | View Code Duplication | public function init_instance_settings() { |
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481 | |||
482 | /** |
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483 | * Processes and saves options. |
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484 | * If there is an error thrown, will continue to save and validate fields, but will leave the erroring field out. |
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485 | * @since 2.6.0 |
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486 | * @return bool was anything saved? |
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487 | */ |
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488 | public function process_admin_options() { |
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509 | } |
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510 |
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: