Are we done on code smells? Guess not. We see several symptoms and situations that make us doubt the quality of our development. Let's look at some possible solutions. Most of these smells are just hints of something that might be wrong. They are not rigid rules. This is part IV. Part I can be found , Part II , Part III is and Part V . here here here Here Code Smell 16 - Ripple Effect Small changes yield unexpected problems. Photo by Jack Tindall on Unsplash Problems Coupling Coupling: The One and Only Software Designing Problem Solutions Decouple. Cover with tests. Refactor and isolate what is changing. Depend on interfaces. Examples Legacy Systems Sample Code Wrong Right Detection It is not easy to detect problems before they happen. and root cause analysis of may help. Mutation Testing single points of failures Tags Legacy Conclusion There are multiple strategies to deal with Legacy and coupled systems. We should deal with this problem before it explodes under our eyes. More info How to Decouple a Legacy System Architecture is the tension between coupling and cohesion. Neal Ford 40+ Thought-Provoking Software Engineering Quotes Code Smell 17 - Global Functions Discouraged by Object-Oriented Programmings, Many mixed languages support it. And developers abuse them. Photo by Mae Mu on Unsplash Problems Coupling Readability Maintainability Testability Solutions Wrap the function in a context object. Examples External Resources Access, Database access, Time and Operating System resources. Sample Code Wrong Right Detection Many modern languages avoid them. For the permissive ones, scope rules can be applied and automatically checked. Tags Global Conclusion Structured programming considers global functions . Yet, we can observe some bad practices cross paradigm boundaries. harmful Relations Singleton and Classes are global points of access. More Info Wikipedia The road to programming hell is paved with global variables. Steve McConnell Code Smell 18 - Static Functions Yet another global access coupled with laziness. Photo by Alex Azabache on Unsplash Problems Coupling Testability Protocol Overloading Cohesion Solutions Class is to create instance. Honor it. Single Responsibility Principle Delegate method to instance. Create stateless objects. Don't call them . helpers Examples Static class methods Static attributes Sample Code Wrong Right Detection We can enforce a policy to avoid static methods (all class methods but constructors). Tags Global Libraries Conclusion Class are globals disguised. Polluting their protocol with "library methods" breaks cohesion and generates coupling. We should extract static with refactorings. Relations Singleton Pattern: The Root of All Evil More info Single Responsibility Principle There is no programming problem that can't be solved with one more level of indirection. John McCarthy Code Smell 19 - Optional Arguments Disguised as a friendly shortcut is another coupling smell. Problems Coupling Unexpected results Side effects Ripple Effect In languages with optional arguments but limited to basic types, we need to set a flag and add an accidental IF (another smell). Solutions Make arguments explicit. All function calls must have same . arity Use if your language supports them. Named Parameters Sample Code Wrong Right Detection Detection is easy if language supports optional arguments. Tags Optional Laziness Conclusion Be explicit. Favor readability over shorter (and more coupled) function call. More info Function Arity How to Decouple a Legacy System The trouble with programmers is that you can never tell what a programmer is doing until it’s too late. Seymour Cray Code Smell 20: Premature Optimization Planning ahead of time needs a crystal ball no developer has. Photo by Markus Spiske on Unsplash Problems Coupling Testability Readability YAGNI Solutions Create great and first. models bijections Create a conclusive benchmark once the model is working. . Design for Performance Use Test Driven Development technique. It always favors the simplest solution. Examples Weird data structures Caches Singletons Sample Code Wrong Right Detection This is a design smell so it can not be detected by mechanical tools (yet). Tags Premature Optimization Antipattern Conclusion Defer performance decisions until functional models are mature enough. Donald Knuth created/compiled the best/fastest algorithms and data structures. With great wisdom he warned us of abuse. Why do we think we are smarter than him? More info c2 wiki Wikipedia Programmers waste enormous amounts of time worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. Donald Knuth Premature optimization is the root of all evil. Donald Knuth And that's it for now. But rest assured, more smells will come.

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