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_Cart 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_Cart, and based on these observations, apply Extract Interface, too.
1 | <?php |
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31 | class WC_Cart extends WC_Cart_Session { |
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32 | |||
33 | /** |
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34 | * This stores the chosen shipping methods for the cart item packages. |
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35 | * @var array |
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36 | */ |
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37 | protected $shipping_methods; |
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38 | |||
39 | /** |
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40 | * Constructor for the cart class. |
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41 | */ |
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42 | public function __construct() { |
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50 | |||
51 | /** |
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52 | * Add an item to the cart. |
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53 | */ |
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54 | public function add_item( $args ) { |
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69 | |||
70 | /** |
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71 | * Add additional fee to the cart. |
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72 | * |
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73 | * @param string $name Unique name for the fee. Multiple fees of the same name cannot be added. |
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74 | * @param float $amount Fee amount. |
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75 | * @param bool $taxable (default: false) Is the fee taxable? |
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76 | * @param string $tax_class (default: '') The tax class for the fee if taxable. A blank string is standard tax class. |
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77 | */ |
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78 | public function add_fee( $name, $amount, $taxable = false, $tax_class = '' ) { |
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99 | |||
100 | /** |
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101 | * Applies a coupon code. |
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102 | * @since 2.7.0 |
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103 | * @param string $coupon_code - The code to apply |
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104 | * @return bool True if the coupon is applied, false if it does not exist or cannot be applied |
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105 | */ |
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106 | public function add_coupon( $coupon_code ) { |
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137 | |||
138 | /** |
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139 | * Returns the contents of the cart in an array. |
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140 | * @return array contents of the cart |
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141 | */ |
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142 | public function get_cart() { |
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151 | |||
152 | /** |
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153 | * Get array of fees. |
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154 | * @return array of fees |
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155 | */ |
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156 | public function get_fees() { |
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159 | |||
160 | /** |
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161 | * Get array of applied coupon objects and codes. |
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162 | * @return array of applied coupons |
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163 | */ |
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164 | public function get_coupons() { |
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167 | |||
168 | /** |
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169 | * Checks if the cart is empty. |
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170 | * @return bool |
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171 | */ |
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172 | public function is_empty() { |
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175 | |||
176 | /** |
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177 | * Empties the cart and optionally the persistent cart too. |
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178 | */ |
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179 | public function empty_cart() { |
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187 | |||
188 | /** |
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189 | * Set the quantity for an item in the cart. |
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190 | * @param string $cart_item_key contains the id of the cart item |
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191 | * @param int $quantity contains the quantity of the item |
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192 | */ |
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193 | public function set_quantity( $item_key, $quantity = 1, $deprecated = true ) { |
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202 | |||
203 | /** |
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204 | * Remove item from cart. |
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205 | * @param string $item_key Cart item key. |
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206 | */ |
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207 | public function remove_cart_item( $item_key ) { |
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210 | |||
211 | /** |
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212 | * Remove a single coupon by code. |
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213 | * @param string $coupon_code Code of the coupon to remove |
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214 | * @return bool |
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215 | */ |
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216 | public function remove_coupon( $coupon_code ) { |
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219 | |||
220 | /** |
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221 | * Remove all coupons. |
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222 | */ |
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223 | public function remove_coupons() { |
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226 | |||
227 | /** |
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228 | * Returns a specific item in the cart. |
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229 | * |
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230 | * @param string $item_key Cart item key. |
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231 | * @return array Item data |
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232 | */ |
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233 | public function get_cart_item( $item_key ) { |
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236 | |||
237 | /** |
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238 | * Restore item from cart. |
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239 | * @param string $item_key Cart item key. |
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240 | */ |
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241 | public function restore_cart_item( $item_key ) { |
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244 | |||
245 | /** |
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246 | * Get all tax classes for items in the cart. |
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247 | * @return array |
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248 | */ |
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249 | public function get_cart_item_tax_classes() { |
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252 | |||
253 | /** |
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254 | * Get weight of items in the cart. |
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255 | * @return int |
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256 | */ |
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257 | public function get_cart_contents_weight() { |
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260 | |||
261 | /** |
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262 | * Get number of items in the cart. |
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263 | * @return int |
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264 | */ |
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265 | public function get_cart_contents_count() { |
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268 | |||
269 | /** |
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270 | * Returns whether or not a coupon has been applied. |
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271 | * @param string $coupon_code |
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272 | * @return bool |
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273 | */ |
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274 | public function has_coupon( $coupon_code = '' ) { |
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278 | |||
279 | /* |
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280 | |-------------------------------------------------------------------------- |
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281 | | Cart shipping calculation. |
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282 | |-------------------------------------------------------------------------- |
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283 | */ |
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284 | |||
285 | /** |
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286 | * Looks through the cart to see if shipping is actually required. |
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287 | * @return bool whether or not the cart needs shipping |
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288 | */ |
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289 | public function needs_shipping() { |
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304 | |||
305 | /** |
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306 | * Should the shipping address form be shown. |
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307 | * @return bool |
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308 | */ |
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309 | public function needs_shipping_address() { |
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312 | |||
313 | /** |
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314 | * Get packages to calculate shipping for. |
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315 | * |
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316 | * This lets us calculate costs for carts that are shipped to multiple locations. |
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317 | * |
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318 | * Shipping methods are responsible for looping through these packages. |
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319 | * |
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320 | * By default we pass the cart itself as a package - plugins can change this. |
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321 | * through the filter and break it up. |
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322 | * |
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323 | * @since 1.5.4 |
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324 | * @return array of cart items |
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325 | */ |
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326 | public function get_shipping_packages() { |
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341 | |||
342 | /** |
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343 | * Uses the shipping class to calculate shipping then gets the totals when its finished. |
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344 | */ |
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345 | public function calculate_shipping() { |
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348 | |||
349 | /** |
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350 | * Given a set of packages with rates, get the chosen ones only. |
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351 | * @since 2.7.0 |
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352 | * @param array $calculated_shipping_packages |
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353 | * @return array |
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354 | */ |
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355 | protected function get_chosen_shipping_methods( $calculated_shipping_packages ) { |
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368 | |||
369 | /* |
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370 | |-------------------------------------------------------------------------- |
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371 | | Cart Totals. |
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372 | |-------------------------------------------------------------------------- |
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373 | */ |
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374 | |||
375 | /** |
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376 | * Calculate totals for the items in the cart. |
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377 | */ |
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378 | public function calculate_totals() { |
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398 | |||
399 | /** |
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400 | * Looks at the totals to see if payment is actually required. |
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401 | * |
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402 | * @return bool |
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403 | */ |
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404 | public function needs_payment() { |
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407 | |||
408 | /** |
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409 | * Gets the order subtotal with or without tax. |
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410 | * @param bool $including_tax |
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411 | * @return string formatted price |
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412 | */ |
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413 | public function get_subtotal( $including_tax = false ) { |
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420 | |||
421 | /** |
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422 | * Gets the order total (after calculation). |
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423 | * @return string formatted price |
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424 | */ |
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425 | public function get_total() { |
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428 | |||
429 | /** |
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430 | * Gets all taxes. |
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431 | * @return array of taxes |
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432 | */ |
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433 | public function get_taxes() { |
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436 | |||
437 | /** |
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438 | * Gets all taxes which will be output. |
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439 | * @return array |
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440 | */ |
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441 | View Code Duplication | public function get_tax_totals() { |
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451 | |||
452 | /** |
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453 | * Get tax row amounts with or without compound taxes includes. |
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454 | * |
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455 | * @param bool $compound True if getting compound taxes |
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456 | * @param bool $round True if getting total to display |
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457 | * @return float price |
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458 | */ |
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459 | public function get_taxes_total( $compound = true, $round = true ) { |
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469 | |||
470 | /** |
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471 | * Get the total tax on the cart. |
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472 | * @return float |
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473 | */ |
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474 | public function get_tax_total() { |
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477 | |||
478 | /** |
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479 | * Get the total tax on shipping. |
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480 | * @return float |
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481 | */ |
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482 | public function get_shipping_tax_total() { |
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485 | |||
486 | /** |
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487 | * Get the total cost of shipping, with or without taxes included. |
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488 | * @param bool $including_tax |
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489 | * @return float |
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490 | */ |
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491 | public function get_shipping_total( $including_tax = false ) { |
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498 | |||
499 | /** |
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500 | * Return the total amount of discount granted by coupons. |
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501 | * @return float |
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502 | */ |
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503 | public function get_cart_discount_total() { |
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506 | |||
507 | /** |
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508 | * Return the tax on the total amount of discount granted by coupons. |
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509 | * @return float |
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510 | */ |
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511 | public function get_cart_discount_tax_total() { |
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514 | |||
515 | /** |
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516 | * Get item totals from totals class. |
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517 | * @return array |
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518 | */ |
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519 | public function get_item_totals() { |
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522 | |||
523 | /** |
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524 | * Get the total discount amount for a specific coupon code. |
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525 | * @param string $code |
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526 | * @param bool $ex_tax |
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527 | * @return float |
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528 | */ |
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529 | public function get_coupon_discount_amount( $code, $ex_tax = true ) { |
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540 | |||
541 | /** |
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542 | * Get the total discount tax amount for a specific coupon code. |
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543 | * @param string $code |
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544 | * @return float |
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545 | */ |
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546 | public function get_coupon_discount_tax_amount( $code ) { |
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551 | } |
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552 |
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: