Code Smells Are a Classic. 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 - XXVIII) here. Let's continue... Code Smell 141 - IEngine, AVehicle, ImplCar Have you ever seen an IEngine in the wild? TL;DR: Don't prefix or suffix your classes Problems Readability Fault Bijection Implementative Names Solutions Remove prefixes and suffixes Name your objects after what they do Context Some languages have cultural conventions related to data types, Abstract classes, or Interfaces. These names load our models with cognitive translations hard to follow. We must . KISS Sample Code Wrong public interface IEngine
{
    void Start();
}

public class ACar 
{

}

public class ImplCar 
{

}

public class CarImpl
{

} Right public interface Engine
{
    void Start();
}

public class Vehicle 
{

}

public class Car 
{

} Detection Automatic [x] If we have a Thesaurus, we can point to awkward names. Exceptions In C#, it's a common practice to put "I" in the name of an interface because, without it, you can't tell whether it is an interface or a class. This is a language smell. Tags Naming Conclusion Use real names for your models. Relations Code Smell 130 - AddressImpl More Info What is in a name: Part II Rehab Credits Photo by Tim Mossholder on Unsplash Some people, when confronted with a problem, think “I know, I’ll use regular expressions.” Now they have two problems. Jamie Zawinski Software Engineering Great Quotes Code Smell 142 - Queries in Constructors Accessing a database in domain objects is a code smell. Doing it in a constructor is a double smell. TL;DR: Constructors should construct (and probably initialize) objects. Problems Coupling Side Effects Solutions Decouple essential business logic from accidental persistence. On persistence classes, run queries in functions other than constructors/destructors. Context On legacy code, the database is not correctly separated from business objects. Constructors should never have side effects. According to the single responsibility principle, they should only build objects valid Sample Code Wrong public class Person {
  int childrenCount; 

  public Person(int id) {
    childrenCount = database.sqlCall("SELECT COUNT(CHILDREN) FROM PERSON WHERE ID = " . id); 
  }
} Right public class Person {
  int childrenCount; 

  // Create a class constructor for the Main class
  public Person(int id, int childrenCount) {
    childrenCount = childrenCount; 
    // We can assign the number in the constructor
    // Accidental Database is decoupled
    // We can test the object
  }
} Detection Semi-Automatic [x] Our linters can find SQL patterns on constructors and warn us. Tags Coupling Conclusion Separation of concerns is key, and coupling is our main enemy when designing robust software. More Info Coupling: The one and only Software Problem Credits <span>Photo by on </span> Callum Hill Unsplash My belief is still, if you get the data structures and their invariants right, most of the code will kind of write itself. Peter Deustch Software Engineering Great Quotes Code Smell 143 - Data Clumps Some objects are always together. Why don't we split them? TL;DR: Make cohesive primitive objects travel together Problems Bad Cohesion Duplicated Code Validation Complexity Readability Maintainability Solutions Extract Class Find small objects Context This smell is friends with primitive obsession. If two or more primitive objects are glued together, with business logic repeated and rules between them, we need to find the existing concept of the . bijection Sample Code Wrong public class DinnerTable
{
    public DinnerTable(Person guest, DateTime from, DateTime to)
    {
        Guest = guest; 
        From = from;
        To = to;
    }
    private Person Guest;
    private DateTime From; 
    private DateTime To;
} Right public class TimeInterval
{
    public TimeInterval(DateTime from, DateTime to)
    {
        // We should validate From < To
        From = from;
        To = to;
    }
}

public DinnerTable(Person guest, DateTime from, DateTime to)
{    
    Guest = guest;
    Interval = new TimeInterval(from, to);
}

// Even Better...

public DinnerTable(Person guest, Interval reservationTime)
{    
    Guest = guest;
    Interval = reservationTime;
} Detection Semi-Automatic [x] Detection based on cohesion patterns is available o a few linters. Tags Cohesion Conclusion Group behavior in the right place and hide the primitive data. Relations Code Smell 122 - Primitive Obsession Code Smell 01 - Anemic Models Code Smell 27 - Associative Arrays More Info Refactoring Guru Wikipedia Credits Photo by Dynamic Wang on Unsplash The heart of the software is its ability to solve domain-related problems for its user. All other features, vital though they may be, support this basic purpose. Eric Evans Software Engineering Great Quotes Code Smell 144 - Fungible Objects We have heard a lot about NFTs. Now, we master the Fungible concept. TL;DR: Respect the . Make fungible what is Fungible in real-world and vice-versa. MAPPER Problems Fault Bijection Over Design Solutions Identify fungible elements on your domains Model them as interchangeable Context According to : Wikipedia Fungibility is the property of a good or a commodity whose individual units are essentially interchangeable and each of whose parts is indistinguishable from another part. In software, we can replace fungible objects with others. When our objects with real ones, we sometimes forget about the model and build over the design. mapping partial Sample Code Wrong public class Person implements Serializable {
    private final String firstName;
    private final String lastName;

    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }
}

shoppingQueueSystem.queue(new Person('John', 'Doe')); Right public class Person  { 
} 

shoppingQueueSystem.queue(new Person());
// The identity is irrelevant for queue simulation Detection Manual [x] This is a semantic smell. We need to understand the model to check whether it is right or not. Tags Over Design Conclusion Make fungible what is fungible and vice-versa. Sounds easy but requires design skills and avoiding accidental complexity. Credits Photo by on Andrey Metelev Unsplash People think that computer science is the art of geniuses but the actual reality is the opposite, just many people doing things that build on each other, like a wall of mini stones. Donald Knuth Code Smell 145 - Short Circuit Hack Don't use boolean evaluation as a readability shortcut. TL;DR: Don't use Boolean comparison for side effect functions. Problems Readability Side Effects Solutions Convert into IFs short circuits Context Smart programmers like to write hacky and obscure code even when there is no strong evidence for this improvement. Premature optimization always hurts readability. Sample Code Wrong userIsValid() && logUserIn();

// this expression is short circuit
// Does not value second statement
// Unless the first one is true

functionDefinedOrNot && functionDefinedOrNot();

// in some languages undefined works as a false
// If functionDefinedOrNot is not defined does
// not raise an error and neither runs Right if (userIsValid()) {
    logUserIn();
}

if(typeof functionDefinedOrNot == 'function') {  
    functionDefinedOrNot();
}
// Checking for a type is another code smell Detection Semi-Automatic [x] We can check if the functions are impure and change the short circuit to an IF. Some actual linters warn us of this problem Tags Premature Optimization Conclusion Don't try to look smart. We are not in the 50s anymore. Be a team developer. Relations Code Smell 140 - Short Circuit Evaluation Code Smell 06 - Too Clever Programmer Code Smell 149 - Optional Chaining Credits Photo by Michael Dziedzic on Unsplash A computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are, in short, a perfect match. Bill Bryson Next article: 5 more code smells.

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How to Find the Stinky Parts of Your Code [Part XXIX]

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