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| work:clean_code_notes [13 years ago - 2012/12/06 19:35] – [Single responsibility principle] aogail | work:clean_code_notes [13 years ago - 2013/01/04 21:54] (current) – [Clean Code notes] aogail | ||
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| ====== Clean Code notes ====== | ====== Clean Code notes ====== | ||
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| + | ===== Liskov substitution principle ===== | ||
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| + | ==== What is a type ==== | ||
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| + | It is a bag of operations | ||
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| + | ==== Subtypes ==== | ||
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| + | A subtype is a type that may be used as another type. | ||
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| + | ==== Refused bequest ==== | ||
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| + | This occurs when a subtype does something unexpected from the point of view of the user of the super type. | ||
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| + | * does not implement method | ||
| + | * method does something unexpected | ||
| + | * etc. | ||
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| + | Every refused bequest/LSP violation is a latent open/closed principle violation. | ||
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| + | ==== Representative rule ==== | ||
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| + | Representatives of things do not share the relationships of the things they represent. So, while geometrically a square is a rectangle, the class that represents a square is not a subtype of the class that represents a rectangle. | ||
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| ===== Single responsibility principle ===== | ===== Single responsibility principle ===== | ||
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| * interface: supports sesifner | * interface: supports sesifner | ||
| * see mastermind example | * see mastermind example | ||
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| + | ===== Open closed principle ===== | ||
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| + | * changing behavior of module should not require changing module' | ||
| + | * problem: need crystal ball to anticipate future changes in order to design to protect yourself using open closed | ||
| + | * solutions: big design up front, agile design | ||
| + | * agile: do simplest thing now, refactor and abstract once customers ask for modifications | ||
| + | * get initial builds in front of customers. Customers will immediately request changes. Developers should change architecture to account for these changes, then refactor to implement new abstractions. | ||
| + | * each iteration should result in more code that conforms to open/ | ||
| + | * | ||
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