![\"patterns\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2022\/06\/patterns.png\")
<\/p>\nToday, I write about the Facade Pattern. The Facade Pattern is a structural pattern and has one purpose: to provide a simplified interface to any complex system.<\/p>\n
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The key idea of the The Facade Pattern is an ideal starting point for decoupling complex systems by introducing layers. Additionally, it can be used as a starting point for deprecating the old interface.<\/p>\n Here are the facts.<\/p>\n <\/p>\n The following example is from Wikibook C++Programming: code patterns design<\/a><\/p>\n <\/p>\n <\/p>\n The class Finally, here is the output of the program:<\/p>\n The Facade is probably the most heavily used Design Pattern in C++.<\/p>\n In general, calling a function that triggers an operating system call applies the Facade Pattern. Here are a few examples:<\/p>\n What are the pros and cons of the Facade Pattern?<\/p>\n A Facade Pattern and a Singleton Pattern are pretty similar. They provide a single access point to a complex system. Consequentially, the pros and cons of the Singleton Pattern also apply to the Facade Pattern. Read more about the pros and cons of the Singleton Pattern in my previous post: “The Singleton: Pros and Cons<\/a>“.<\/p>\n In my next post, I present the remaining structural pattern from the book “Design Patterns: Elements of Reusable Object-Oriented Software”<\/a>: the Proxy Pattern. The Proxy Pattern<\/a> is used as a placeholder for accessing another object.<\/p>\n <\/p>\n <\/p><\/p>\n","protected":false},"excerpt":{"rendered":" Today, I write about the Facade Pattern. The Facade Pattern is a structural pattern and has one purpose: to provide a simplified interface to any complex system.<\/p>\n","protected":false},"author":21,"featured_media":6385,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[379],"tags":[],"class_list":["post-6473","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-patterns"],"_links":{"self":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts\/6473","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/users\/21"}],"replies":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/comments?post=6473"}],"version-history":[{"count":0,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts\/6473\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/media\/6385"}],"wp:attachment":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/media?parent=6473"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/categories?post=6473"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/tags?post=6473"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Facade Pattern<\/code> is to provide a simplified interface to a complex system, consisting of a set of interfaces. A facade defines a higher-level interface that makes the subsystem easier to use. The high-level interface intends not to support all use cases of the complex system, but only the most important. Despite the Facade Pattern for the simplified interface, it is often still possible to use the complex system directly.<\/p>\nFacade Pattern<\/h2>\n
Purpose<\/h3>\n
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Use Case<\/h3>\n
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Structure<\/h3>\n
![\"Facade\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2022\/11\/Facade.png\")
<\/p>\nFacade<\/code><\/strong><\/p>\n\n
Package<\/code><\/strong><\/p>\n\n
Example<\/h3>\n
\n\/\/ from https:\/\/en.wikibooks.org\/wiki\/C%2B%2B_Programming\/Code\/Design_Patterns#Facade<\/span>\r\n\r\n#include <string><\/span>\r\n#include <iostream><\/span>\r\n\r\nusing<\/span> namespace<\/span> std;\r\n\r\nclass<\/span> Alarm \/\/ (2) <\/span><\/span><\/span>\r\n{\r\npublic:<\/span>\r\n\tvoid<\/span> alarmOn()\r\n\t{\r\n\t\tcout <<<\/span> \"Alarm is on and house is secured\"<\/span><<<\/span>endl;\r\n\t}\r\n\r\n\tvoid<\/span> alarmOff()\r\n\t{\r\n\t\tcout <<<\/span> \"Alarm is off and you can go into the house\"<\/span><<<\/span>endl;\r\n\t}\r\n};\r\n\r\nclass<\/span> Ac <\/span>\/\/ (3)<\/span><\/span><\/span>\r\n{\r\npublic:<\/span>\r\n\tvoid<\/span> acOn()\r\n\t{\r\n\t\tcout <<<\/span> \"Ac is on\"<\/span><<<\/span>endl;\r\n\t}\r\n\r\n\tvoid<\/span> acOff()\r\n\t{\r\n\t\tcout <<<\/span> \"AC is off\"<\/span><<<\/span>endl;\r\n\t}\r\n};\r\n\r\nclass<\/span> Tv \/\/ (4)<\/span><\/span><\/span>\r\n{\r\npublic:<\/span>\r\n\tvoid<\/span> tvOn()\r\n\t{\r\n\t\tcout <<<\/span> \"Tv is on\"<\/span><<<\/span>endl;\r\n\t}\r\n\r\n\tvoid<\/span> tvOff()\r\n\t{\r\n\t\tcout <<<\/span> \"TV is off\"<\/span><<<\/span>endl;\r\n\t}\r\n};\r\n\r\nclass<\/span> HouseFacade \/\/ (1)<\/span><\/span>\r\n{\r\n\tAlarm alarm;\r\n\tAc ac;\r\n\tTv tv;\r\n\r\npublic:<\/span>\r\n\tHouseFacade(){}\r\n\r\n\tvoid<\/span> goToWork() \/\/ ( \r\n\t{\r\n\t\tac.acOff();\r\n\t\ttv.tvOff();\r\n\t\talarm.alarmOn();\r\n\t}\r\n\r\n\tvoid<\/span> comeHome() \/\/ (5) Facade \r\n\t{\r\n\t\talarm.alarmOff();\r\n\t\tac.acOn();\r\n\t\ttv.tvOn();\r\n\t}\r\n};\r\n\r\nint<\/span> main<\/span>()\r\n{\r\n\tHouseFacade hf;\r\n\r\n\t\/\/Rather than calling 100 different on and off functions thanks to facade I only have 2 functions...<\/span>\r\n\thf.goToWork();\r\n\thf.comeHome();\r\n}\r\n<\/pre>\n<\/div>\nHouseFacade<\/code> (line 1) provides simplifies the usage of the classes Alarm<\/code>, Ac<\/code>, and TV<\/code> (lines 2 to 4). The simplified interface consists of the two member functions goToWork<\/code> (line 5) and comeHome<\/code> (line 6). Both member functions encapsulate the original interface’s underlying member functions and guarantee that the member functions are called in the correct sequence.<\/p>\n![\"facadePattern\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2022\/11\/facadePattern.png\")
<\/p>\nKnown Uses<\/h3>\n
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Related Patterns<\/h3>\n
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Pros and Cons<\/h3>\n
Pros<\/h4>\n
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Cons<\/h4>\n
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What’s Next?<\/h2>\n