It smells because there are likely many instances where it could be edited or improved. Most of these smells are just hints of something that might be wrong. Therefore, they are not required to be fixed per se… (You should look into it, though.) Previous Code Smells You can find all the previous code smells (Part i - XXXII) . here Let's continue... Code Smell 161 - Abstract/Final/Undefined Classes Your classes are abstract, final, or undefined TL;DR: If your language has the right tool, your classes should be either abstract or final. Problems Subclassification for Code Reuse Classes with concrete subclass just one Liskov Substitution Violation Problem Yo-Yo Solutions Declare all your leaf classes as and the rest of them as . final abstract Context Managing hierarchies and composition is the main task of a good software designer. Keeping hierarchies healthy is crucial to favor cohesion and avoid . coupling Sample Code Wrong public class Vehicle
{
  // the class is not a leaf. Therefore it should be abstract
    
  // an abstract method that only declares, but does not define the start 
  // functionality because each vehicle uses a different starting mechanism
  abstract void start();
}

public class Car extends Vehicle
{
  // the class is a leaf. Therefore it should be final
}

public class Motorcycle extends Vehicle
{
  // the class is a leaf. Therefore it should be final
} Right abstract public class Vehicle
{
  // the class is not a leaf. Therefore it must be abstract  
 
  //an abstract method that only declares, but does not define the start 
  //functionality because each vehicle uses a different starting mechanism
  abstract void start();
}

final public class Car extends Vehicle
{
  // the class is a leaf. Therefore it is final
}

final public class Motorcycle extends Vehicle
{
  // the class is a leaf. Therefore it is final
} Detection Automatic [x] Since this is enforced by static analysis, we can't do it with most available tools. Tags Subclassification Conclusion We should look back at our classes, and start qualifying them either as abstract or final. There are no valid cases for two concrete classes, one subclassifying the other. Relations Code Smell 11 - Subclassification for Code Reuse Code Smell 136 - Classes With just One Subclass Code Smell 37 - Protected Attributes Code Smell 58 - Yo-yo Problem More Info Coupling - The one and only software design problem Deep Subclasses Disclaimer Code Smells are just my . opinion Credits Photo by on William Bossen Unsplash When the final design seems too simple for the amount of work you've put in, then you know you're done. Brady Clark Code Smell 162 - Too Many Parentheses Parentheses are free of charge. Aren't they? TL;DR: Use as few parentheses as possible. Problems Readability Syntactic complexity Solutions Remove all not necessary parentheses Context We read code from left to right (at least, in western culture). Parentheses often break this flow, adding cognitive complexity. Sample Code Wrong schwarzschild = ((((2 * GRAVITATION_CONSTANT)) * mass) / ((LIGHT_SPEED ** 2))) Right schwarzschild = (2 * GRAVITATION_CONSTANT * mass) / (LIGHT_SPEED ** 2) Detection Automatic [x] This is a fully automated code smell. It is based on syntax trees. Many tools detect it. Exceptions On some complex formulas, we can add extra parenthesis for terms’ readability. Tags Readability Bloaters Relations Code Smell 02 - Constants and Magic Numbers Conclusion We write code once and read it too many times. Readability is king. Credits Photo by on Nick Fewings Unsplash If someone claims to have the perfect programming language, he is either a fool or a salesman or both. Bjarne Stroustrup Code Smell 163 - Collection in Name Have you ever seen a CustomerCollection? TL;DR: Don't use 'collection' in your name. It is too abstract for concrete concepts. Problems Readability Abstraction Abuse Bad Naming Solutions Rename the collection with a specific name. Context Naming is very important. We need to deal a lot with collections. Collections are amazing since they don't need nulls to model the absence. An empty collection is polymorphic with a full collection. We avoid and . nulls IFs We often use bad and vague names instead of looking for good names in the . MAPPER Sample Code Wrong for (var customer in customerCollection) {

    // iterate with current customer

}



for (var currentCustomer in customersCollection) {

    // iterate with current customer

} Right for (var customer in customers) {

    // iterate with current customer

} Detection Semi-Automatic [x] All linters can detect a bad naming like this. It can also lead to false positives, so we must be cautious. Tags Naming Conclusion We need to care for all our clean code, variables, classes, and functions. Accurate names are essential to understand our code. Relations Code Smell 134 - Specialized Business Collections More Info What exactly is a name - Part II Rehab Credits Photo by on Mick Haupt Unsplash Alzheimer's Law of Programming: Looking at code you wrote more than two weeks ago is like looking at code you are seeing for the first time. Dan Hurvitz Code Smell 164 - Mixed Indentations Tabs vs Spaces. The most significant computer problem. TL;DR: Don't mix indentation styles Problems Readability Code consistency Standards violation Solutions Choose one of them. Stick to it. Enforce it with code standards tests. Share the rules on all the codebases. Use an IDE like VSCode or WebStorm that doesn't include tabs at all. Context Whenever I publish an article many people don't care about the sample intent and rush to point out indentation mistakes. Choosing one standard over the other will be a great solution. Spaces always count as one. Tabs can count as many different options. Sample Code Wrong function add(x, y) {

// --->..return x + y;



      return x + y;

}



function main() {

// --->var x = 5,

// --->....y = 7;



    var x = 5,

        y = 7;

} Right function add(x, y) {

// --->return x + y;

    return x + y;

} Detection Automatic [x] Any parser can enforce this rule. Exceptions Some languages like Python consider indent as part of the syntax. In these languages, indentation is not accidental since it changes code semantics. Tags Code Standards Conclusion There's been so much debate on this subject. The smell is related to mixing them, not about using one instead of another. Some IDEs automatically convert one convention to the other one. Relations Code Smell 48 - Code Without Standards More Info ES Lint Whatever the device you use for getting your information out, it should be the same information. Tim Berners-Lee Code Smell 165 - Empty Exception Blocks On Error resume next was the first thing I learned in my first job. TL;DR: Don't avoid exceptions. Handle Them. Problems Principle Violation Fail Fast Solutions Catch the exception, and deal with it explicitly. Context In the early programming days, we privileged the systems running before error handling. We have evolved. Sample Code Wrong # bad

import logging



def send_email(): 

  print("Sending email") 

  raise ConnectionError("Oops")

  

try:

  send_email() 

except: 

  # AVOID THIS

pass Right import logging



logger logging.getLogger(__name___)

try:

  send_email()

except ConnectionError as exc:

  logger.error(f"Cannot send email {exc}") Detection Automatic [x] Many linters warn us on empty exception blocks Exceptions If we need to skip and ignore the exception, we should document it explicitly. Tags Exceptions Conclusion Prepare to deal with the errors. Even if you decide to do nothing, you should be explicit with this decision. Relations Code Smell 132 - Exception Try Too Broad More Info Fail Fast On Error Resume Next Package Credits Photo by on James Best Unsplash Thank you @ Jan Giacomelli Twitter Optimization hinders evolution. Everything should be built top-down, except the first time. Simplicity does not precede complexity, but follows it. Alan Perlis Software Engineering Great Quotes 5 more code smells are coming soon…

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