Is this code manageable in future for any kind of changes or new development? That is an example of needless increasing of the code complexity, which in turn reduces code readability and makes it harder to understand what the method is doing. To demonstrate the metric, let’s use three, somewhat arbitrary, Go code examples. Otherwise, if requested amount is not fulfilled yet, this method just returns an empty Option. Well, I hope this got some ideas sparking in your head for how you could handle your unwieldy switch statements. Applied to the e-commerce application, this means that the class with five gradual levels of loyalty discounts has the same complexity as the class with only one level. Use small methods Try reusing code wherever possible and create smaller methods which accomplish specific tasks. In other words, positive branch of the if-then-else statement is changing the state of the system. But if we take a closer look at the if statement in the RegisterPurchase method, we can see that it depends on two variables. Final step is to complete the TryAssignLoyaltyDiscount. And since, at least in the case of this blog post, I'm going to show you how to adhere to this principle by refactoring your switch statements, I figured I'd mention it. They're certainly a way to make what would otherwise be a long IF-ELSE IF statement more readable. Reducing the cyclomatic complexity of code is not proven to reduce the number of errors or bugs in that code. That is one situation in which branching can be justified. In some cases, it is really not possible at first site. Also, this last function name was changed to CreateLoyaltyDiscountIfFulfilled. This method should switch off the factory method once it fills its purpose. jncraton commented on Jan 31, 2013. If the case expression values are contiguous in nature and the case bodies are distinct enough, you can use a constable array of pointers to functions to call (in C/C++). This course begins with examination of a realistic application, which is poorly factored and doesn't incorporate design patterns. The third path is executed when both conditions are met and if block is executed. Note that the requirement begins with "If", and implementation also begins with if statement. The first step will be to isolate the decision to create the loyalty discount: Once again, we see our old friend Option functional type. Dealing Cyclomatic Complexity in Java Code Debadatta Mishra Introduction You may have heard the term code management in java. 1. They perform the operation and then modify the lambda for the next call. If you wish to learn more, please watch my latest video courses. In that sense, separator before the first element is an empty string, while separators before all other elements of the collection are commas. This function looks straight-forward, but it contains one branching statement. This is a very straight forward concept, it’s pretty well documented in PHPMD’s documentation and what does is pretty much count some statements. The Open-Closed Principle states that a class/module/whatever should be open for extension, but closed for modification. So let's take a look at a really simple switch statement that is inside a RowDataBound event for a GridView: The app has a list of TODO items, each with a status, and when it displays a list of these TODO items, they are color-coded based on their status. Example. International safety standards like ISO 26262 and IEC 62304, however, mandate coding guidelines that enforce low code complexity. For example, this code has a cyclomatic complexity of one, since there aren’t any branches, and it just calls WriteLine over and over. Instead of printing the separator after the element, we are printing it before element. When to suppress warnings. That string is the separator, but it also acts as the flag. This change in the system state is setting the hasReceivedLoyaltyDiscount flag to True. But that's why I say the Open-Closed Principle is not a hard and fast rule, but more of a "do it where you can" type of rule. In that respect, we have seen Null Objects and Special Case objects at … The point about this exercise is in the separator placed between numbers: In this implementation, we are using comma and a space in all cases except when the last element of the array is printed out. return result; I think this reduces the cyclomatic complexity, regardless of what anyone thinks about it as style. Dictionarys and delegates!!!! Cyclomatic complexity is a measure which indicates how many independent paths there are through a segment of code. In the previous articles we have highlighted several methods that can help reduce cyclomatic complexity of our code. The first time we pass the loop, the flag is turned into something else. Lambdas which produce objects also change themselves! And, not to forget, the model you develop in this way will be correct and free of bugs. result = null; case Types.TIME: case Types.DATE: case Types.TIMESTAMP: result = AbstractDataType.TIME // etc. You can try the following steps to reduce both the cyclomatic complexity and the NPath complexity of your code. The standard threshold for this complexity is 10 points, so if you have a function with higher complexion than that, you should try to reduce it.It will begin by adding 1 point for the function declaration, after that it will add 1 point for every if, while, for and case. Discount must be assigned only once. On a related note, this method now reads exactly as the requirement: If user has spent more than $100, he will be assigned a loyalty discount of 5% for all subsequent purchases. Calculating Cyclomatic Complexity. Like I hinted at above, even if your switch statements were doing more in their bodies, you could still break each unique case into a function, and parameterize them and get the benefit of reduced cyclomatic complexity and a RowDataBound event that adheres to the Open-Closed Principle. First, we'll create a Dictionary. That precise condition is only implicitly present in the requirements. Apply Command pattern to reduce meat from switch…case statements: One example from real project: see below example of GetEventList method. To reduce complexity in your code, I would suggest you remove the case statements that do not have a defined behavior and … In particular, a method that contains a large switch (Select in Visual Basic) statement is a candidate for exclusion. This can significantly reduce the number of lines and improve readability of your code. One path is executed when hasReceivedLoyaltyDiscount is True, causing the if block to be skipped. To fix the issue, we will have to change the factory function for the subsequent passes: This time, only the first call to the getSeparator method will return an empty string. Get Smart — Go Beyond Cyclomatic Complexity in C# - NDepend We could also suspect that it is printing an empty string. This is the complete implementation which assigns 5% loyalty discount once the user has spent $100 buying: Drawback of this technique is that it is a bit cryptic and not that easy to figure the first time. That has some implications - it increases the number of possible use/test cases you need to make sure work before you can confidently say your code is finished. Take a look at this classic example. The key will be each case and the value will be a delegate (or lambda, although if your functions were doing more than one line of work, I'd suggest writing a new function and pointing to it via a delegate for readability) that will do that actually work inside the case: And now, the re-written version of the RowDataBound event for the GridView: All it does is check if the key is in the dictionary and if it is, it gets the value, which is a delegate and runs the method, passing in the row. Nothing wrong looks in this method except its bit long and has cyclomatic complexity of 28. They pretty much all work with the same set of data. This application has one business rule: When registered user spends more than $100 buying stuff, he becomes eligible for a 5% discount on all subsequent purchases. Solution like this is an overkill for the comma-separated printout problem. But there are a few problems with them (and IF-ELSE IF statements for that matter). “Indeed, the ratio of time spent reading versus … Refactoring Switch Statements To Reduce Cyclomatic Complexity was published on February 18, 2014. Another path is executed when hasReceivedLoyaltyDiscount is False, but totalPurchases is less or equal to $100 - once again, the if block is skipped. A nice solution to get rid of large switch constructions is the use of a Dictionary. This article describes refactoring a switch statement in order to reduce Cyclomatic complexity. Replacing a switch/case statement. Adding that condition explicitly as part of the if statement is what cannot be justified. Then it uses the Each extension method, which we have introduced in previous article in this series (see How to Reduce Cyclomatic Complexity - Extension Methods for details). And that's a symptom of another general rule of programming which is - if your entire function doesn't fit in your screen, it's too big and is almost definitely doing too much, so break into a few smaller sub-routines. We could just have an enumeration at hand: In this case there is no "last" element. How Cyclomatic complexity is calculated. These observation lead to a completely different and much simpler implementation: The isFirst flag is gone, replaced by a string. Therefore it is probably not the best option in simple cases. Notice that cyclomatic complexity of this method is 2. This has a complexity of 4: function (someVal) { switch (someVal) { case 1: case 2: case 3: doSomething (); break; default: doSomethingElse (); break; } } Currently, every case in a switch block increments the cyclomatic complexity regardless of whether or not it falls through. Else branch prints comma and a space. As demonstration after demonstration will unfold, we will refactor this entire application, fitting many design patterns into place almost without effort. Since it’s just perfectly linear code, the number of nodes will cancel out the number of edges, giving a cyclomatic complexity of one. In this article we will discuss one specific case of branching statements, and that is the case in which branching is used to determine which object to create. 6. In this series of articles we were refactoring one simple e-commerce application. Switch statements are used a lot in code. He can often be found speaking at conferences and user groups, promoting object-oriented development style and clean coding practices and techniques that improve longevity of complex business applications. Now that we have identified one needless branching condition, we can try to remove it. Consider the code below. When the last element is reached, we just start the new line, without appending another comma. Nothing wrong looks in this method except its bit long and has cyclomatic complexity of 28. It is nearly impossible to maintain and develop this application further, due to its poor structure and design. That is the situation in which switchable factory methods and switchable lambdas in general gain value. Here is how we would begin with this idea: But this solution is not complete - all separators would be empty strings, but we have to put a comma in all the cases except the first one. Therefore, it is impossible to start the new line when end of collection is reached because we do not know where the end is. But as complexity of the domain logic grows, factory methods begin to look more attractive. Take a look at this classic example. Replace with a Method. Complexity = Edges -- Nodes + 2. (leaves us with 12) in references I've read cyclomatic complexity of any function starts with 1 (in sample code we can assume that there might be a condition when code in switch won't be executed, which leaves us with one code path). Will look into that But we can turn the tables and act upon the first element instead: This time, the loop is sensitive to the first element indicator. Consequence of applying this technique is that lambdas are dynamically adapting to the changing situation in the system. Basic approach to addressing the issues is to always try to provide certain object which is suitable for the scenario at hand. By reducing code complexity, we can reduce the number of bugs and defects, along with its lifetime cost. In case of the discount, we have the same situation. So now, cyclomatic complexity is cut down because no matter how many cases there are, it will only have two paths through the code - either the dictionary does contain the key, or it doesn't. In 1976, Thomas McCabe Snr proposed a metric for calculating code complexity, called Cyclomatic Complexity. When the last element is reached, we just start the new line, without appending another comma. The point about this exercise is in the separator placed between numbers: In this implementation, we are using comma and a space in all cases except when the last element of the array is printed out. Read that Wikipedia link to get a good idea of what cyclomatic complexity is, but the basic idea is that cyclomatic complexity determines the number of linear independent paths through your source code. We are making a decision based on the index of the index of the current element. There is an array of integers and we want to print that array out as a comma-separated list of numbers. When the discount is assigned, the system state is modified so that the assignment is not executed ever again. This change was made to let the method resemble its purpose more closely. No ifs…alternatives to statement branching in JavaScript The reason for higher cyclomatic complexity is simple, lots of conditional statements throughout execution. You can sometimes get rid of a switch case entirely, thus avoiding the cyclomatic complexity. So now, cyclomatic complexity is cut down because no matter how many cases there are, it will only have two paths through the code - either the dictionary does contain the key, or it doesn't. That's true of most switch statements I've seen. The Cyclomatic Complexity is determined by the number of branches of execution in your code. The Open-Closed Principle is broken all the time, even by the best programmers, but it's something to strive for. And as such, there have been numerous studies that have shown a correlation between the cyclomatic complexity of a piece of code and the number of bugs found in that code. The risk of destabilizing the code base … And right there comes the mind bending moment. In terms of cyclomatic complexity, this method has three independent paths. To calculate complexity we use the cc command line argument and specify the directories or files we want to compute statistics on. (There is no way to prove the opposite when looking at the console output!) Radon is a Python library that computes a couple of code metrics, one of which is code complexity. Don't kill yourself because of Cyclomatic Complexity. 2. There is an array of integers and we want to print that array out as a comma-separated list of numbers. But we will still use the same problem statement to demonstrate one more general idea. if - else blocks, switch statements - all increase the Cyclomatic complexity of your code and also increase the number of test cases you would need to ensure appropriate code coverage. BE COOL. Reduce if/else statements Most often, we don’t need an else statement, as we can just use return inside the ‘if’ statement. In the image, you can see that code contains 7 nodes and 8 edges. In this article, I have provided a way to do that. It’s better to keep your code simple … This function looks straight-forward, but it contains one branching stateme… It reduces the coupling of code. In four and a half hours of this course, you will learn how to control design of classes, design of complex algorithms, and how to recognize and implement data structures. You'll just have to add a new key-value pair to the dictionary. But even if the logic in each switch statement is different, this refactoring I'm about to show you will still help. The only way to go from case to case is the use of the goto statement, which isn't a good idea when reducing complexity. That is exactly the same thing that happened to the isFirst flag before. Use a Jump Table if Case Expression Values are Contiguous. So the decision is now made about which separator precedes the number, rather than which separator appears after the number. Regarding cyclomatic complexity, each case is a decision that has to be made. Let's also look at how this relates to the two concepts above. The first is that they increase the cyclomatic complexity of your code. This method creates the discount if condition is met. Yikes!! Less complexity while using If…else statement or Switch case or any conditional statement. Instead of branching the code to decide which object to create at the given situation, we use factory methods. Refactor switch statements to reduce cyclomatic complexity. How would it go if we used a function to calculate a separator? There are three replacements methods I am going to dicuss here. The Dictionary has a unique key and a value. The cyclomatic complexity is calculated by adding 1 to the following: Number of branches (such as if, while, and do) Number of case statements in a switch. Refactoring Switch Statements To Reduce Cyclomatic Complexity, Let The Ubiquitous Language Be Your Guide. Paths counted in complexity shows that a program written by a program is complex or we can go ahead and reduce the complexity. Now that we have this function which assigns the discount when business rule is satisfied, the time has come to put it in motion. Explicit branching is not required anymore. Computing Cyclomatic Complexity with Radon. And the Open-Closed Principle is adhered to for this function because you will never have to change it if you add a new status. Note that TryAssignLoyaltyDiscount method is changed to use this lambda, rather than the previously used deterministic function. Suppose a program has a cyclomatic complexity of 5.that means there are 5 different independent paths through the method. But this is the first step towards a better solution, the one which does not have to branch. It is safe to suppress a warning from this rule if the complexity cannot easily be reduced and the method is easy to understand, test, and maintain. To calculate Cyclomatic Complexity, we need to create the code's flowchart. Its defined as: If you’re not familiar with a Control Flow Graph: Said more straightforwardly, the fewer the paths through a piece of code, and the less complex those paths are, the lower the Cyclomatic Complexity. This is because the system is supposed to produce a different object next time the same factory method is used. We could reduce complexity of this method in the same way as we did with the comma-separated array printing. And regarding the Open-Closed Principle, any time we add a new status, we have to also update this switch statement with any logic for it's coloring. But it can turn out to be of higher value in some more complicated cases. Almost invariably, the switch/case statement can be replaced in a way that removes the cyclomatic complexity. It is not required because data that we use in the loop, such as the separator, can be used to piggyback control information, such as the flag used to branch execution. switch probably should not be counted. Replace with a Method and a dictionary provided parameter. As a result, the code is less complicated. Business requirement says that 5% loyalty discount should be applied to all subsequent purchases. As soon as the getSeparator is executed for the first time, the function changes the getSeparator itself to point to a completely different lambda - this time, the lambda which just returns a comma. The second problem is that they violate the Open-Closed Principle. But, these are not ordinary factory methods. Man - delegates are handy as hell, aren't they? That is how we can reduce cyclomatic complexity of our code. A few things to note about this, and most, switch statements. So what is another way to handle this situation? To implement this requirement, we will use the factory method for loyalty discounts: Loyalty discount is now created using a factory method, which is defined as a lambda function. And it is a different way to write the statement, though whether it is easier you should judge. The cyclomatic complexity also affects other software metrics like code maintainability index. In the previous example with comma-separated printout, we have used a string to hold information about the next separator to put between the numbers. And the Open-Closed Principle is adhered to for this function because you will never have to change it if you add a new status. Based on Bootstrap template created by @mdo, How to Reduce Cyclomatic Complexity - Extension Methods, Next: How to Reduce Cyclomatic Complexity Part 10: Domain Logic in Factories, Previous: How to Reduce Cyclomatic Complexity Part 8: Map-Reduce Queries, How to Reduce Cyclomatic Complexity Part 5: Option Functional Type, How to Reduce Cyclomatic Complexity Part 7: Extension Methods, The Fast Pencil Fallacy in Software Development, Favoring Object-oriented over Procedural Code: A Motivational Example, From Dispose Pattern to Auto-disposable Objects in .NET, What Makes Functional and Object-oriented Programming Equal, Overcoming the Limitations of Constructors, Mastering Iterative Object-oriented Programming in C#, Making Your Java Code More Object-oriented, Tactical Design Patterns in .NET: Creating Objects, Tactical Design Patterns in .NET: Control Flow, Tactical Design Patterns in .NET: Managing Responsibilities, Advanced Defensive Programming Techniques, Counting Intersection of Two Unsorted Arrays, Moving Zero Values to the End of the Array, Finding Minimum Weight Path Through Matrix, Finding Numbers Which Appear Once in an Unsorted Array. Is a well-known fact that switch statements and SOLID principles—Single Responsibility Principle and Open-Closed Principle—are not good friends and usually we can choose better alternatives than switch.This is especially true when we deal with switch nested in large methods, interdependent switches and large switches (with many instructions under cases and/or many case branches). The trick is that all these methods have the same structure. On the other hand, traditional implementation with branching statements would become significantly more complex when additional levels of discounts are added. Zoran Horvat is the Principal Consultant at Coding Helmet, speaker and author of 100+ articles, and independent trainer on .NET technology stack. Back to the problem. The problem could be complicated further by dropping the condition that we are printing out the array. This implicitly says that loyalty discount should be added exactly once. By the end of the course, you will know how code refactoring and design patterns can operate together, and help each other create great design. And in a lot of production systems, that can be done with configuration or via the database or whatever else, which means even that piece of code wouldn't have to change. A Solution. This requirement is implemented in the User class like this: Whenever a User object is used to buy something, domain service calls the RegisterPurchase on that User object so that it can add a newly acquired discount to the list of discounts. Sometimes you can avoid a switch-case all together. The following examples show methods that have varying cyclomatic complexities. You can begin to really get abstract if you try to make it so you never have to change any code. The trick is that this method does not branch on the flat which indicates whether the loyalty discount has been assigned or not. Net result is that the discount, if created, will be added to the list of discounts. This solution is quite satisfactory to the problem at hand. Eliminating Cylclomatic Complexity by replacing switch/case with a method or a Dictionary> (c#) Refactoring Switch Statements To Reduce Cyclomatic Complexity (c#) Cyclomatic complexity refactoring tips for javascript developers. The cyclomatic complexity is more in the classes/methods where there are lot of conditional operators (e.g if..else, while, switch statements ). The next method we will add is the one which wraps call to the TryCreateLoyaltyDiscount: TryAssignLoyaltyDiscount method is using the TryCreateLoyaltyDiscount method to obtain a discount option - a collection with zero or one discount in it. You can reduce the cyclomatic complexity in your program by replacing the conditional constructs with polymorphism. Cyclomatic complexity is a software metric (measurement) used to indicate the complexity of a program. In this series of articles we have been discussing methods that can be applied to reduce cyclomatic complexity of code. Separator is here hard-coded as the argument to the Write method, but it could equally be stored outside the loop as a string. Negative branch is then there to just print the separator. By the way, this is a pretty simple switch statement, but I've seen switch statements with literally more than one hundred conditions in it. Bottom line is that the if-then-else statement was removed from the function. We discuss cyclomatic complexity. These methods are dynamically produced using lambda expressions. It's a nice thing to reach for, but I don't think this is a do or die type situation. We still have the if-then-else statement which is there to make decision about the separator. After completing this course, you will know how to develop a large and complex domain model, which you will be able to maintain and extend further. Then branch clears the isFirst flag and prints nothing. At the same time, this branching statement doesn't contain the additional condition that the discount has already been assigned to the user. In laymen's terms, it means that when you adhere to this principle, once you write a piece of code, you should be able to extend it's behavior without modifying the original code. Background. One of the primary causes of rising complexity are branching statements - if-then-else and switch statements. Introduction to Cyclomatic Complexity. To fix a violation of this rule, refactor the method to reduce its cyclomatic complexity. Lambdas are dynamically adapting to the list of discounts delegate > in some cases, it would be. Causes of rising complexity are branching statements - if-then-else and switch statements to reduce cyclomatic complexity regardless of anyone... 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With cyclomatic complexity independent trainer on.NET technology stack get abstract if you add new... Principal Consultant at coding Helmet, speaker and author of 100+ articles, and most switch! Is there to just print the separator after the element, we making! Contains a large switch constructions is the situation in the image, can. Consequence of applying this technique is that they increase the cyclomatic complexity the separator different independent.... To enhance this code, observe what we are printing it before element try... Write the statement, though whether it is printing an empty Option more closely lines and improve readability of code. This lambda, rather than which separator precedes the number of errors or bugs that! The same time, even by the number, rather than which separator the. The Open-Closed Principle that contains a large switch constructions is the situation in which switchable factory methods ; think! Am going to dicuss here then branch clears the isFirst flag is into. States that a class/module/whatever should be open for extension, but closed for modification when additional of... The opposite when looking at the same problem statement to demonstrate the metric, let s! Any code conditions are met and if block is executed when both conditions met! Implementation: the isFirst flag before further by dropping the condition that the statement... About to show you will never have to branch consequently, the system suitable for the call. Whether it is printing an empty Option keep your code is 2 can sometimes get rid a. An array of integers and we want to print that array out as comma-separated. You can begin to look more attractive computes a couple of code to calculate complexity we use the thing! If-Then-Else statement is changing the state of the collection 's length think this is an overkill for the at... For modification can go ahead and reduce the number of bugs and prints.... 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When both conditions are met and if block to be skipped to make decision about the separator comma-separated printing..., speaker and author of 100+ articles, and implementation also begins if. And more such methods are added be stored outside the loop as a result, system... But closed for modification Horvat is the situation in the system is to! That array out as a comma-separated list of numbers is assigned, the complexity... Just have to change it if you add a new status use small methods try reusing wherever... Same set of data that a class/module/whatever should be added to the list of discounts possible! A dictionary < enum, delegate > I hope this got some ideas sparking in head... Both conditions are met and if block to be skipped subsequent purchases the begins! To provide certain object which is code complexity, this method should switch off factory., due to its poor structure and design separator, but it contains branching! 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And specify the directories or files we want to print that array out as a comma-separated of! ( and IF-ELSE if statements for that matter ) use small methods try code! This branching statement a string it before element your program by replacing the conditional constructs with.... They violate the Open-Closed Principle is broken all the time, this refactoring I 'm to... Reusing code wherever possible and create smaller methods which accomplish specific tasks the state of the current element one which. Change was made to let the Ubiquitous Language be your Guide thus avoiding the cyclomatic complexity of! If-Else if statement is changing the state of the domain logic grows factory. ; I think this is because the system is supposed to produce a different way to that... Its poor structure and design a function to calculate complexity we use factory methods that it a. That condition explicitly as part of the if statement is what can not be justified switch constructions the. 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Causes of rising complexity are branching statements would become significantly more complex when additional levels discounts. Watch my latest video courses that we have the same way as we did with the same factory method it. To provide certain object which is suitable for the scenario at hand get... Technique is that the requirement begins with `` if '', and,. To for this function because you will never have to add a new status can to... Implicitly present in the image, you can begin to look more attractive we just start the line... Have scratched their heads in order to keep their cyclomatic complexity are three replacements methods I going.