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Top 10 Reasons That Make Your Code Smell

Top 10 Reasons That Make Your Code Smell


The term code smells were first introduced by Kent Beck in the 1990s. It is a common programming term that refers to violations in the fundaments of software development. Code smells are not to be confused with bugs or errors. The term is used to refer to practices that can negatively affect the quality of your code. Coding is not just about getting outputs but also involves getting programs to perform as efficiently and effectively as possible. 


What Makes Your Code Smell and How Can You Remove Smells

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Here are some of the most common code smells that you may be committing when developing software. 

Long Functions:

Short function programs are the ones that are easiest to understand and last the longest. People have known since the dawn of programming that the longer a function is, the more difficult it is to comprehend. Subroutine calls in older languages had a high overhead, which discouraged people from using small functions. For in-process calls, modern languages have practically removed this overhead. Since you have to adjust meaning to see what the particular feature or function does, there is always overhead for the reader of the code.

Development environments that allow you to switch between a function call and its declaration easily, or to see both functions at once, can help you skip this stage, but good naming is the real key to making small functions easy to understand. You usually do not need to look at the body of the function if it has a good name. Functions should be clear about what they do and should concentrate on a single, discrete task so that they can be reused and re-adjusted as and when needed. Typically, as the length of a function increases, so does its complexity, and the code becomes less maintainable.

Long Parameter Lists:

A method call with a long parameter list is a code smell. It suggests that something is not quite right with the implementation of the code. There is no hard and fast law on how many ordered lists are too many. More than three or four is usually considered excessive as it reduces the readability and understanding of the code and makes it more prone to bugs and errors. Too complex methods can result in a long parameter list. Another reason that can be an evident cause of long parameter lists is to reduce dependencies on others.

Depending on the situation and the scenario, the solution to get out of the same varies. This problem is generally solved by introducing a parameter object. To do so, you need to create a new object from the long list of parameters that match together and transfer it as a single argument. This has a lot of advantages because we can specify the parameter object before calling the function, and the property order doesn’t matter. This is something we should always keep in mind when creating a parameter list. It also improves code readability and can reduce previously undetected replication

Confusing Names:

It can be difficult to learn all of the different naming conventions from language to language, particularly when you are first getting started with various web development languages. It is even more perplexing when developers disagree on what constitutes the best practice for naming. It is generally believed that a variable name that is more complicated than a noun is a code smell. This is particularly because when the reach of a variable is so broad and complex that a simple noun would be vague, we tend to give it a compound name.

A broad, complicated scope is also a code smell. And so, it is always recommended to give your variables and methods specific single word names to keep your methods and classes clean and solid and to avoid ambiguity. Your code should always look clear and concise and the only way of doing that is by giving more structured, uncomplicated names that are easy to understand and comprehend. Your code should always be able to perform the refactoring. If your code is unable to perform refactoring, it means that your scope is too complex and big.

A good method should handle up to five variables, and a good class should contain up to five properties. To summarize, the particular conventions you select are much less critical than maintaining consistency in your use. Many development teams, in reality, create their own convention guidelines for new hires.

Temporary Field:

If you have a class instance variable that has only been used once, you have a code smell called Temporary Fields. Temporary fields are often generated in the case of such algorithms that involve a large number of inputs. Rather than creating a large number of parameters in the process, the programmer decides to create fields in the class for this information. These fields are only included in the algorithm and are otherwise ignored.

This type of code is difficult to comprehend and use. You will expect to see data in object fields, but they are almost always empty for some reason. Temporary fields, as well as any code that interacts with them, can be placed in a separate class using Extract Class. To put it another way, you are generating a method object, which achieves the same result as replacing a method with a method object. Another way of dealing with temporary fields is by introducing a Null Object and using it in place of the conditional code that was previously used to search for the presence of temporary field values.

Data Clumps:

When more than one piece of data is often found together, it is referred to as a data clump. Identical classes of variables appear in various sections of the code at times such as parameters for connecting to a database. These clumps can be separated into groups. These data classes are often the result of weak program structure. If you want to be certain that any data is a data clump, simply remove one of the data values and see if the other values still make sense. If this is not the case, it is a good indication that this set of variables can be merged into a single object.

With different situations, the ways to deal with data clumps also change. If the field of the class contains repeated data, you can use Extract Class to separate the fields into their own class. Or you can introduce a Parameter Object to set them apart as a class if the same data clumps are passed in the parameters of methods. This improves code comprehension and organization. Instead of being strewn around the code, operations on specific data are now gathered in one location. As a result, the code size is also reduced

Duplicated Code:

While there are projects that allow you to duplicate chunks of code from a common repository that is publicly available, it is not a reliable practice. Many programmers who lift code off of sources like GitHub do not verify the integrity of the code. While it is okay to make use of old code, refactoring code should also involve checking and auditing your duplicated code. You need to refactor code before implementing it into your project. You can also create abstract classes for commonly used code or adopt unique design patterns to ensure you do not have code smells. 

You may like: What is duplicate code?


Mismanaged Class Size:

SOLID design principles are meant to help developers achieve flexible, maintainable, and understandable software. Most programmers implement SOLID design principles but often mismanage the single-responsibility principle. The most common code smell arises out of programmers who end up writing bloated classes with thousands of lines of code. It is very difficult to maintain bloated code which is why having a single-responsibility principle in your coding guidelines is a must.

Other programmers, on the other hand, take the single-responsibility principle too seriously and have small class sizes that are hard to refactor or maintain. Your class sizes should be moderate in size and should make sense. Striking the right balance when creating classes is important to ensure you do not have too little or too many lines of code in your program.


Poor Method Names:

Developers tend to overlook naming for their methods. All methods end up being named in a generic fashion which makes conveying anything to code auditors very difficult. While it can be difficult to find the right name for your method without deep diving into your code, poor method names make it even harder for developers who want to understand your code.

There needs to be consistency in your method naming to ensure developers can simply look at the names and understand what they do. But you also need to not be obsessed with poor method names which can be too difficult to interpret. Names that are full of text or unreadable can make auditing or understanding code very difficult. 



It is important to leave comments in your code to help developers understand your code. But leaving too many comments ruins the flow of your code. Comments can be very helpful when it comes to explaining the logic behind specific parts of your code. But developers tend to overuse comments and there is absolutely no reason to leave comments for every step of your program. It is a bad idea to have excessive noise in your code and it can render reading your code very difficult. Self-documenting coding practices is the best way forward when it comes to leaving comments.

Your code should be self-explanatory and allow developers to understand it with minimal comments. Documentation comments are important but overusing them can lead to problems. Your comments should focus on why you chose to write a certain piece of code instead of what it does. Most developers who audit are fully capable of understanding code but helping them understand your coding methods is very helpful. 


Conditional Statements:

Your strategy patterns need to be backed up by conditional statements. Most developers do not make use of conditional statements while on the other hand, some developers make use of statements far too often. You should avoid having large conditional blocks in your code that make reading code difficult. Large blocks of conditional statements can bloat your code and make your code spell. It is important to have the right strategy and keep your code as streamlined as possible. You can refer to similar programs that are in the market for reference. 


Recommended read: Everything you need to know about Code Smells


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These are the top five signs that you need to look out for to find out if you have code smells. It is important to keep your code as concise as possible while also leaving enough comments to ensure developers understand your code and can easily audit it. It is your responsibility to prevent code smells and adopt the best coding practices. Making a habit of preventing code smell reduces the amount of effort it takes to audit, patch, or copy over code for future projects. 

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