![\"\"](\"https:\/\/demensdeum.com\/blog\/wp-content\/uploads\/2019\/06\/bridge.jpg\")
<\/p>\nThe Bridge pattern is a structural design pattern. It allows you to abstract the implementation of class logic by moving the logic into a separate abstract class. Sounds simple, right?<\/p>\n
<\/p>\n
Let’s say we are implementing a spam bot that should be able to send messages to different types of messengers.
We implement it using a common protocol:<\/p>\n
protocol User {\n let token: String\n let username: String\n}\n\nprotocol Messenger {\n var authorize(login: String, password: String)\n var send(message: String, to user: User)\n}\n\nclass iSeekUUser: User {\n let token: String\n let username: String\n}\n\nclass iSeekU: Messenger {\n\n var authorizedUser: User?\n var requestSender: RequestSender?\n var requestFactory: RequestFactory?\n\n func authorize(login: String, password: String) {\n authorizedUser = requestSender?.perform(requestFactory.loginRequest(login: login, password: password))\n }\n \n func send(message: String, to user: User) {\n requestSender?.perform(requestFactory.messageRequest(message: message, to: user)\n }\n}\n\nclass SpamBot {\n func start(usersList: [User]) {\n let iSeekUMessenger = iSeekU()\n iSeekUMessenger.authorize(login: \"SpamBot\", password: \"SpamPassword\")\n \n for user in usersList {\n iSeekUMessennger.send(message: \"Hey checkout demensdeum blog! http:\/\/demensdeum.com\", to: user)\n }\n }\n}\n<\/code><\/pre>\n<\/div>\nNow let’s imagine a situation where a new, faster messaging protocol for the iSekU messenger is released. To add a new protocol, you will need to duplicate the iSekU bot implementation, changing only a small part of it. It is unclear why this should be done if only a small part of the class logic has changed. This approach violates the DRY principle; with further development of the product, the lack of flexibility will make itself known through errors and delays in the implementation of new features.
Let’s move the protocol logic into an abstract class, thus implementing the Bridge pattern:<\/p>\n
\nprotocol User {\n let token: String\n let username: String\n}\n\nprotocol Messenger {\n var authorize(login: String, password: String)\n var send(message: String, to user: User)\n}\n\nprotocol MessagesSender {\n func send(message: String, to user: User)\n}\n\nclass iSeekUUser: User {\n let token: String\n let username: String\n}\n\nclass iSeekUFastMessengerSender: MessagesSender {\n func send(message: String, to user: User) {\n requestSender?.perform(requestFactory.messageRequest(message: message, to: user)\n }\n}\n\nclass iSeekU: Messenger {\n\n var authorizedUser: User?\n var requestSender: RequestSender?\n var requestFactory: RequestFactory?\n var messagesSender: MessengerMessagesSender?\n\n func authorize(login: String, password: String) {\n authorizedUser = requestSender?.perform(requestFactory.loginRequest(login: login, password: password))\n }\n \n func send(message: String, to user: User) {\n messagesSender?.send(message: message, to: user)\n }\n}\n\nclass SpamBot {\n\n var messagesSender: MessagesSender?\n\n func start(usersList: [User]) {\n let iSeekUMessenger = iSeekU()\n iSeekUMessenger.authorize(login: \"SpamBot\", password: \"SpamPassword\")\n \n for user in usersList {\n messagesSender.send(message: \"Hey checkout demensdeum blog! http:\/\/demensdeum.com\", to: user)\n }\n }\n}\n<\/code><\/pre>\n<\/div>\nOne of the advantages of this approach is undoubtedly the ability to expand the functionality of the application by writing plugins\/libraries that implement abstracted logic without changing the code of the main application.
What’s the difference with the Strategy pattern? Both patterns are very similar, but Strategy describes switching *algorithms*, while Bridge allows switching large parts of *any logic, no matter how complex*.<\/p>\n
Sources<\/h3>\n
https:\/\/refactoring.guru\/ru\/design-patterns\/bridge <\/a><\/p>\nSource code<\/h3>\n
https:\/\/gitlab.com\/demensdeum\/patterns\/<\/a><\/a> p><\/p>\n","protected":false},"excerpt":{"rendered":"The Bridge pattern is a structural design pattern. It allows you to abstract the implementation of class logic by moving the logic into a separate abstract class. Sounds simple, right? Let’s say we are implementing a spam bot that should be able to send messages to different types of messengers.We implement it using a commonContinue reading “Pattern Bridge”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[61,52],"tags":[106,95],"class_list":["post-2042","post","type-post","status-publish","format-standard","hentry","category-techie","category-tutorials","tag-bridge","tag-patterns","entry"],"translation":{"provider":"WPGlobus","version":"3.0.2","language":"en","enabled_languages":["en","ru","zh","de","fr","ja","pt"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"ru":{"title":true,"content":true,"excerpt":false},"zh":{"title":true,"content":true,"excerpt":false},"de":{"title":true,"content":true,"excerpt":false},"fr":{"title":true,"content":true,"excerpt":false},"ja":{"title":true,"content":true,"excerpt":false},"pt":{"title":true,"content":true,"excerpt":false}}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/posts\/2042","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/comments?post=2042"}],"version-history":[{"count":12,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/posts\/2042\/revisions"}],"predecessor-version":[{"id":3955,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/posts\/2042\/revisions\/3955"}],"wp:attachment":[{"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/media?parent=2042"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/categories?post=2042"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/wp-json\/wp\/v2\/tags?post=2042"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}