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 Jetpack_Photon_Static_Assets_CDN 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 Jetpack_Photon_Static_Assets_CDN, and based on these observations, apply Extract Interface, too.
1 | <?php |
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21 | class Jetpack_Photon_Static_Assets_CDN { |
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22 | const CDN = 'https://c0.wp.com/'; |
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23 | |||
24 | /** |
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25 | * Sets up action handlers needed for Jetpack CDN. |
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26 | */ |
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27 | public static function go() { |
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28 | add_action( 'wp_print_scripts', array( __CLASS__, 'cdnize_assets' ) ); |
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29 | add_action( 'wp_print_styles', array( __CLASS__, 'cdnize_assets' ) ); |
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30 | add_action( 'admin_print_scripts', array( __CLASS__, 'cdnize_assets' ) ); |
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31 | add_action( 'admin_print_styles', array( __CLASS__, 'cdnize_assets' ) ); |
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32 | add_action( 'wp_footer', array( __CLASS__, 'cdnize_assets' ) ); |
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33 | } |
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34 | |||
35 | /** |
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36 | * Sets up CDN URLs for assets that are enqueued by the WordPress Core. |
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37 | */ |
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38 | public static function cdnize_assets() { |
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39 | global $wp_scripts, $wp_styles, $wp_version; |
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40 | |||
41 | /** |
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42 | * Filters Jetpack CDN's Core version number and locale. Can be used to override the values |
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43 | * that Jetpack uses to retrieve assets. Expects the values to be returned in an array. |
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44 | * |
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45 | * @since 6.6 |
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46 | * |
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47 | * @param array $values array( $version = core assets version, i.e. 4.9.8, $locale = desired locale ) |
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48 | */ |
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49 | list( $version, $locale ) = apply_filters( |
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50 | 'jetpack_cdn_core_version_and_locale', |
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51 | array( $wp_version, get_locale() ) |
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52 | ); |
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53 | |||
54 | if ( self::is_public_version( $version ) ) { |
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55 | $site_url = trailingslashit( site_url() ); |
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56 | View Code Duplication | foreach ( $wp_scripts->registered as $handle => $thing ) { |
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57 | if ( wp_startswith( $thing->src, self::CDN ) ) { |
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58 | continue; |
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59 | } |
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60 | $src = ltrim( str_replace( $site_url, '', $thing->src ), '/' ); |
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61 | if ( self::is_js_or_css_file( $src ) && in_array( substr( $src, 0, 9 ), array( 'wp-admin/', 'wp-includ' ) ) ) { |
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62 | $wp_scripts->registered[ $handle ]->src = sprintf( self::CDN . 'c/%1$s/%2$s', $version, $src ); |
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63 | $wp_scripts->registered[ $handle ]->ver = null; |
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64 | } |
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65 | } |
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66 | View Code Duplication | foreach ( $wp_styles->registered as $handle => $thing ) { |
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67 | if ( wp_startswith( $thing->src, self::CDN ) ) { |
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68 | continue; |
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69 | } |
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70 | $src = ltrim( str_replace( $site_url, '', $thing->src ), '/' ); |
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71 | if ( self::is_js_or_css_file( $src ) && in_array( substr( $src, 0, 9 ), array( 'wp-admin/', 'wp-includ' ) ) ) { |
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72 | $wp_styles->registered[ $handle ]->src = sprintf( self::CDN . 'c/%1$s/%2$s', $version, $src ); |
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73 | $wp_styles->registered[ $handle ]->ver = null; |
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74 | } |
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75 | } |
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76 | } |
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77 | |||
78 | self::cdnize_plugin_assets( 'jetpack', JETPACK__VERSION ); |
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79 | if ( class_exists( 'WooCommerce' ) ) { |
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80 | self::cdnize_plugin_assets( 'woocommerce', WC_VERSION ); |
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81 | } |
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82 | } |
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83 | |||
84 | /** |
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85 | * Sets up CDN URLs for supported plugin assets. |
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86 | * |
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87 | * @param String $plugin_slug plugin slug string. |
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88 | * @param String $current_version plugin version string. |
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89 | * @return null|bool |
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90 | */ |
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91 | public static function cdnize_plugin_assets( $plugin_slug, $current_version ) { |
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141 | |||
142 | /** |
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143 | * Returns cdn-able assets for a given plugin. |
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144 | * |
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145 | * @param string $plugin plugin slug string. |
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146 | * @param string $version plugin version number string. |
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147 | * @return array |
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148 | */ |
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149 | public static function get_plugin_assets( $plugin, $version ) { |
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211 | |||
212 | /** |
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213 | * Checks a path whether it is a JS or CSS file. |
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214 | * |
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215 | * @param String $path file path. |
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216 | * @return Boolean whether the file is a JS or CSS. |
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217 | */ |
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218 | public static function is_js_or_css_file( $path ) { |
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219 | return ( false === strpos( $path, '?' ) ) && in_array( substr( $path, -3 ), array( 'css', '.js' ), true ); |
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220 | } |
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221 | |||
222 | /** |
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223 | * Checks whether the version string indicates a production version. |
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224 | * |
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225 | * @param String $version the version string. |
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226 | * @param Boolean $include_beta_and_rc whether to count beta and RC versions as production. |
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227 | * @return Boolean |
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228 | */ |
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229 | public static function is_public_version( $version, $include_beta_and_rc = false ) { |
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240 | } |
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241 | Jetpack_Photon_Static_Assets_CDN::go(); |
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242 |
This checks looks for assignemnts to variables using the
list(...)
function, where not all assigned variables are subsequently used.Consider the following code example.
Only the variables
$a
and$c
are used. There was no need to assign$b
.Instead, the list call could have been.