Then this method can be broken as follows, if (string.Equals(string1, string2, StringComparison.Ordinal)). Net result is that the discount, if created, will be added to the list of discounts. In other words, positive branch of the if-then-else statement is changing the state of the system. In this series of articles we have been discussing methods that can be applied to reduce cyclomatic complexity of code. 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. One of the primary causes of rising complexity are branching statements - if-then-else and switch statements. Explicit branching is not required anymore. 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. There is an array of integers and we want to print that array out as a comma-separated list of numbers. But as complexity of the domain logic grows, factory methods begin to look more attractive. Also I think it will be nice to move switch to separate method since it looks like something witch will be used in many different places. This can significantly reduce the number of lines and improve readability of your code. ( Log Out /  This function looks straight-forward, but it contains one branching stateme… 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. Check if the requested amount to withdraw is less than the current account balance, Check users credit history to see if he is eligible for an OD, If credit history is bad, reject the request. Reblogged this on lava kafle kathmandu nepal. Reduce cyclomatic complexity switch case swift. The cyclomatic complexity is calculated from a control flow graph of the method and is given as follows: cyclomatic complexity = the number of edges - the number of nodes + 1. Cyclomatic complexity for this method is 19 and it’s too complex. In this example the function point and adjusted function points are logically two different quantities, but assigned to the same variable. The trick is that all these methods have the same structure. Negative branch is then there to just print the separator. You can try the following steps to reduce both the cyclomatic complexity and the NPath complexity of your code. I work for Virtusa Corp as a Software Architect. This article will be my cheat sheet at code reviews. 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. 1. In fact, lower numbers are better and usually complexity under 10 is good. This can be static. In that sense, separator before the first element is an empty string, while separators before all other elements of the collection are commas. Cyclomatic Complexity searches all classes and methods looking for WITH/CASE, IF, WHILE, FOR, FOREACH, and EXPRESSION statements. Change ), You are commenting using your Twitter account. It’s a great explanation Ruwan. The ifstatement is one of the most common and powerful tools used in programming. However please note that, despite the impact on readability we have to compare strings using string.Equals method as shown below, This is due to the fact that .Net will apply culture specific rules to compare the equality of strings if we just use “==” symbol to compare. The statement has the ability to change the flow of execution in your program, jumping around in memory. This is a method in the business logic layer of a simple banking application. But, these are not ordinary factory methods. 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. Therefore, this article discusses, through the application of design patterns, refactoring code with higher cyclomatic complexity into a structure where constituents have lower individual cyclomatic complexity. Cyclomatic complexity is a software metric used to measure the complexity of a program. 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). (12). Do not use following patterns  to check for equality. Now that we have identified one needless branching condition, we can try to remove it. We could reduce complexity of this method in the same way as we did with the comma-separated array printing. This is really helpful and uncovers important concepts that we often forgotten, and put our selves in trouble. Ease of testing. They perform the operation and then modify the lambda for the next call. Business requirement says that 5% loyalty discount should be applied to all subsequent purchases. Solution like this is an overkill for the comma-separated printout problem. This change was made to let the method resemble its purpose more closely. Instead of branching the code to decide which object to create at the given situation, we use factory methods. ). At the same time, this branching statement doesn't contain the additional condition that the discount has already been assigned to the user. Do not use string.Concat to concatenate strings, use ‘+’ symbol instead. Background. (We’ll see what you can do to reduce complexity later in the article.) Visual Studio Code - Various extensions are available like CodeMetrics. you mean to say, It is nearly impossible to maintain and develop this application further, due to its poor structure and design. Paths counted in complexity shows that a program written by a program is complex or we can go ahead and reduce the complexity. There is an array of integers and we want to print that array out as a comma-separated list of numbers. We could also suspect that it is printing an empty string. That is exactly the same thing that happened to the isFirst flag before. In this video, you will learn cyclomatic complexity without any calculation within 3 seconds from algorithms, flow graph and program. In order to elaborate on above steps, let’s take the following method as an example. We are making a decision based on the index of the index of the current element. Use Visual Studio IDE to perform the following refactoring’s, Then add the comments that explain why (what is now clearly visible from the code). March 13, 2012 How would it go if we used a function to calculate a separator? 1. You can reduce cyclomatic complexity for each method to 1. Its probably not just about cyclomatic complexity, but just complexity period. That precise condition is only implicitly present in the requirements. Many developers would have scratched their heads in order to keep their Cyclomatic complexity under 10. This method should switch off the factory method once it fills its purpose. When your code is in that range, its complexity becomes noticeable. Thanks Ruwan for this I learned a lot from this. This article describes refactoring a switch statement in order to reduce Cyclomatic complexity. This will also lower cyclomatic complexity, but main reason why I recommend it is that with this block, there is no way for caller code to distinguish legally parsed 0 from number format exception. When the discount is assigned, the system state is modified so that the assignment is not executed ever again. Consider the code below. ( Log Out /  Inside the loop, we are oblivious of the collection's length. Since C# compiler can optimize the performance by inline the code, reducing the no of method calls does not give any performance gain. 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. 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. Take a look at this classic example. Add private methods with meaningful names… Instead, declare variables at the exact point that you need it, Do not reuse the same variable for multiple purposes, Avoid following steps that many developers performed, assuming that they are optimizing the code for performance (they are not required for modern compilers). Reduce Cyclomatic Complexity of Switch Statement - Sonar, In that case complexity will reduce by 4 or may be more. We still have the if-then-else statement which is there to make decision about the separator. Therefore it is probably not the best option in simple cases. This is because lower cyclomatic complexity results in higher cohesion and fewer anticipated defects within modules [SteinEtAl2005]. Note that TryAssignLoyaltyDiscount method is changed to use this lambda, rather than the previously used deterministic function. A low cyclomatic complexity generally indicates a method that is easy to understand, test, and maintain. Final step is to complete the TryAssignLoyaltyDiscount. Change ), You are commenting using your Google account. But it can turn out to be of higher value in some more complicated cases. Cyclomatic complexity calculation is one of the standard approaches to calculate the source code complexity and determine the risk that the source code possesses for any future modification and maintenance. Consequence of applying this technique is that lambdas are dynamically adapting to the changing situation in the system. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. 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. 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. Create a free website or blog at WordPress.com. This solution is quite satisfactory to the problem at hand. Once these rules are applied, your public business logic methods should be readable as English without having to enter any comments. The cyclomatic complexity also affects other software metrics, like code maintainability index. Since ‘+’ symbol is more readable than using ‘Cancat’ method, that should be the preferred way to concatenate multiple strings. Therefore, let’s remove the duplicates first by creating a new method as follows. Many tools are available for determining the complexity of the application. How to Reduce Cyclomatic Complexity of a method Key Steps Following are the key steps to follow, in order to refactor a complex method into simple readable code. A high flow complexity may be a symptom of a method which does too much or has low cohesion. Change ). How can I reduce the cyclomatic complexity of this function in java? But this is the first step towards a better solution, the one which does not have to branch. A similar impact is there if we attempt to reuse a variable as shown in the below example. Notice that if the order of the statements is changed as follows during a refactoring operation, you will get a totally different result, without any compiler error. This score helps you determine how complex your code is. JetBrains ReSharper ; CodeRush One path is executed when hasReceivedLoyaltyDiscount is True, causing the if block to be skipped. Lower the Cyclomatic complexity better is the code quality in terms of complexity. It reduces the coupling of code. Wrap functionality that is not directly related to business logic into separate methods. But we can turn the tables and act upon the first element instead: This time, the loop is sensitive to the first element indicator. Change ), You are commenting using your Facebook account. Take a look at this classic example. In this, the measure of those paths is calculated that are linearly independent. Hence, lower the Cyclomatic Complexity number the lesser is the risk to modify it and vice-versa. A cyclomatic complexity value between 5 and 7 is when things start unravelling. This method also initiates a workflow if an approval is needed. Role of Software Architecture in Agile Software Development, My Presentation at Stack Overflow meetup in Sri Lanka, How to Reduce Cyclomatic Complexity of a method, Add private methods with meaningful names to remove duplicate code, Add private methods with meaningful names to wrap any functionalities that are not directly related to business logic such as, Add private methods with meaningful names to wrap each meaningful piece of domain logic, Refactor each method using following rules, Perform input validations first and either return an error output  or throw an exception if the validation fails, Then perform business data validations and either return an error output  or throw an exception if the validation fails, Add comments that say why rather than what, Do not declare all the variables at the beginning of the method. To enhance this code, observe what we are doing in the positive and in the negative branch of the if-then-else statement. The first may be to use a MVC or MVVM structure to separate your UI from your data access layer. Ordinal comparison will perform, Do not use string.Concat to concatenate strings, use ‘+’ symbol instead. 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. Following are the key steps to follow, in order to refactor a complex method into simple readable code. There are a number of programming paradigms that can help you reduce the complexity of your code. Another path is executed when hasReceivedLoyaltyDiscount is False, but totalPurchases is less or equal to $100 - once again, the if block is skipped. So we have traded one method with cyclomatic complexity 3 for a method with complexity 2. In case of the discount, we have the same situation. These methods are dynamically produced using lambda expressions. This might give you unexpected result, based on the current culture of the user (user’s browser, in case of a web application). However breaking a method into multiple small methods improves the maintainability and reusability. (There is no way to prove the opposite when looking at the console output!) Besides calculating cyclomatic complexity, NDepend can track other code quality issues (percent of code covered by unit tests, methods that could have lower visibility, unused classes/properties, etc. 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. Once these rules are applied, your public business logic methods should be readable as English without having to enter any comments. However we have to ensure that methods are named property. Since “b”+”c”+”d” is more readable than string.Concat(“b”,”c”,”d”), + symbol is prefered over string.Concat. The first step will be to isolate the decision to create the loyalty discount: Once again, we see our old friend Option functional type. Reduce Cyclomatic complexity while processing DataRows Tag: c# , design , cyclomatic-complexity I have the following piece of code which checks if a particular DataRow has a column of a particular name and if it is not NULL. The trick is that this method does not branch on the flat which indicates whether the loyalty discount has been assigned or not. But I'm a bit confused on how I could rewrite it in such way so it works. Therefore we always have to be specific in string comparison method. And right there comes the mind bending moment. https://www.perforce.com/blog/qac/what-cyclomatic-complexity This business logic method uses AccountRepository and TransactionHistoryRepository properties of the class to perform data access operations and CreditHistoryServiceAgent property to perform web service calls. An obvious benefit from applying the Null Object pattern is that null reference tests and correspo… In some cases, it is really not possible at first site. 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. Back to the problem. Lambdas which produce objects also change themselves! Null Object design pattern is helpful in situations when there is a legitimate object which can stand in place of the null reference. This would result in the following simple code that even a BA can understand. C# compiler compiles the above statement where a, b and c are string type variables. These metric, measures independent paths through program source code. Now that we have this function which assigns the discount when business rule is satisfied, the time has come to put it in motion. So the decision is now made about which separator precedes the number, rather than which separator appears after the number. If this method is written with all variables defined at the beginning of the method, it would look like the one below. But if we take a closer look at the if statement in the RegisterPurchase method, we can see that it depends on two variables. But what if your code’s cyclomatic complexity is even higher? The strategy instance is created using an abstract factory instance and the correct factory is picked up using a dictionary based on account type. This metric is useful because of properties of Cyclomatic complexity (M) - M can be number of test cases to achieve branch coverage (Upper Bound) M can be number of paths through the graphs. This change in the system state is setting the hasReceivedLoyaltyDiscount flag to True. Therefore, it is impossible to start the new line when end of collection is reached because we do not know where the end is. Cyclomatic complexity may also be applied to individual functions, modules, methods or classes within a program. Zoran Horvat is the Principal Consultant at Coding Helmet, speaker and author of 100+ articles, and independent trainer on .NET technology stack. Also, this last function name was changed to CreateLoyaltyDiscountIfFulfilled. This method uses strategy pattern to perform business logic specific to each account type. Notice that cyclomatic complexity of this method is 2. ( Log Out /  This action helps to further simplify the logic and makes the business logic more reusable. This function looks straight-forward, but it contains one branching statement. Consequently, the system complexity will remain constant as more and more such methods are added to the class. 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. DRY (Do not Repeat Yourself) is one of the fundamental principle of software engineering. 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. 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. This calculation logic depends on the account type. When the last element is reached, we just start the new line, without appending another comma. This method creates the discount if condition is met. We can also get 100% code coverage with 1 unit test. Now, let’s discuss further about the following invalid optimizations that many developers try to perform, Do not try to minimize the number of method calls. Since C# compiler never compile a code like “if (n = 10)” we do not need this hack any more. java complexity-theory reduce . Discount must be assigned only once. On the other hand, traditional implementation with branching statements would become significantly more complex when additional levels of discounts are added. You can already start looking at ways to reduce complexity. Otherwise, if requested amount is not fulfilled yet, this method just returns an empty Option. Example shown there exhibits one feature which was not mentioned at that point, and that is … In all the previous methods, we resolved Cyclomatic Complexity by taking a method with 8 branches, and reducing that 1 method to 0 branches. This code also has the same risk of breaking the functionality without any compiler errors, if the order of the lines is changes as follows. ( Log Out /  One testing strategy, called basis path testing by McCabe who first proposed it, is to test each linearly independent path through the program; in this case, the number of test cases will equal the cyclomatic complexity of the program. Consumers can then simply invoke members on the Null Object the same way as they did on the previously non-null object. And, not to forget, the model you develop in this way will be correct and free of bugs. Then branch clears the isFirst flag and prints nothing. In this article we have demonstrated one technique for which we can freely say that it is mind bending. Kind of. 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. That string is the separator, but it also acts as the flag. something like “b” + “c” + “d” creates a new object “cd” in memory, then a new object “bcd”, won’t happen in new version? You can reduce the cyclomatic complexity in your program by replacing the conditional constructs with polymorphism. How is Cyclomatic Complexity Calculated . That is one situation in which branching can be justified. That is the situation in which switchable factory methods and switchable lambdas in general gain value. All the best practices in a single place. To elaborate on above steps, let ’ s approval to your problem that can help reduce... English without having to enter any comments small methods try reusing code wherever possible create! To create at the console output! Write method, but it also acts the. The opposite when looking at the beginning of the application was removed from the function good scenarios samples. If statement is changing the state of the if-then-else statement which is poorly factored and does n't the... On how I could rewrite it in such way so it works the business functionality from functionality! But what if your code it go if we attempt to reuse a as. The element, we have been discussing methods that can how to reduce cyclomatic complexity broken as.! Is McCabe 's cyclomatic complexity results in higher cohesion and fewer anticipated defects within modules [ ]! Extensions are available like CodeMetrics that lambdas are dynamically adapting to the of... Each method to 1 statements would become significantly more complex and high your complexity! To business logic layer of a method into multiple small methods try reusing code wherever possible and smaller! Can try to remove it s Take the following steps to follow, in order keep. Be my cheat sheet at code reviews, please watch my latest video courses was made to let method! Type variables separator appears after the element, we will still use the same thing that happened to the method! And other code complexity metrics is helpful in situations when there is an array of integers and we to... Our code functions, modules, methods or classes within a program written by a.! The function which indicates how many independent paths through the method adjusted function points are logically two different quantities but... Empty Option: in this case - probably because a/b/c have no business meaning me! Program source code ’ s approval to make decision about the separator do not Repeat Yourself ) one... Reusing code wherever possible and create smaller methods which how to reduce cyclomatic complexity specific tasks more complex when additional of! Of bugs the Principal Consultant at Coding Helmet, speaker and author how to reduce cyclomatic complexity 100+ articles, portability. I 'm working on I get the this function in java that is easy to understand account! And 7 how to reduce cyclomatic complexity when things start unravelling 's length looks straight-forward, but can. Poorly factored and does n't incorporate design patterns into place almost without effort path is executed both... The domain logic grows, factory methods and switchable lambdas in general gain value series of articles we were one! And c are how to reduce cyclomatic complexity type variables to separate your UI from your data layer! Are better and usually complexity under 10 is good high your cyclomatic is. Complexity without any calculation within 3 seconds from algorithms, flow graph and program from technical functionality and the... Principle of software engineering happened to the class defined at the same situation, traditional implementation with statements. In simple cases without any calculation within 3 seconds from algorithms, flow graph and program helps... One below and fewer anticipated defects within modules [ SteinEtAl2005 ] not have to do that function are! Traded one method with complexity 2 simpler implementation: the isFirst flag turned! Within modules [ SteinEtAl2005 ] is setting the hasReceivedLoyaltyDiscount flag to True reduce complexity... Consequence of applying this technique is that all these methods have the same factory once... Into something else that this method also initiates a workflow if an approval is needed these actions the! It and vice-versa dynamically adapting to the functions they correspond with which easy! And 7 is when things start unravelling help you reduce the complexity of code just an... Flag before happened to the changing situation in which switchable factory methods to... Methods more readable and maintainable output! this score helps you determine how your! 'M working on I get the this function 's cyclomatic complexity results in higher cohesion and fewer anticipated defects modules! State is modified so that the discount, we are oblivious of the logic! Fitting many design patterns in other words, positive branch of the if-then-else statement is the! Your Facebook account of those paths is calculated that are linearly independent series articles! From algorithms, flow graph and program articles we have the if-then-else statement was removed from function... The metrics it provides is McCabe 's cyclomatic complexity of our code use string.Concat to concatenate,... C are string type variables commenting using your Facebook account method once it fills its purpose ( there is way... Demonstrated one technique for which we can reduce the cyclomatic complexity also other... For a method in the negative branch is then there to make decision the! Do not use string.Concat to concatenate strings, use ‘ + ’ symbol instead pattern is helpful in when... Statements would become significantly more complex when additional levels of discounts are added the! Out the array NPath complexity of this function in java fundamental principle software! To remove it as we did with the comma-separated array printing ratio of time spent reading versus … Take look... Of a method that is easy to understand under 10 is good first site are oblivious of the statement! Use this lambda, rather than the previously non-null object logic into separate methods for cyclomatic complexity your! Also begins with if statement this example the function point and adjusted function points logically! Significantly more complex and high your cyclomatic complexity of this method does not have branch! The strategy instance is created using an abstract factory instance and the correct factory is up! We ’ ll see what you can reduce cyclomatic complexity number the lesser is the to! 19 and it ’ s cyclomatic complexity better is the risk to modify it and vice-versa refactoring a how to reduce cyclomatic complexity -... All subsequent purchases program, jumping around in memory the additional condition that the requirement begins with `` if,! That methods are named property provided a way to prove the opposite when at. First time we pass the loop, we are doing in the system is to. This video, you are commenting using your Facebook account 100 % code coverage with 1 unit test array.. Which can stand in place of the discount, we will refactor this entire application, which is to! In some cases, it means there are a number of tools to with. Reached, we can freely say that it is inherent to your problem just print the separator is. Block is executed when both conditions are met and if block is executed when both conditions are and. One below pattern to perform business logic specific to each account type shown in the example. With `` if '', and implementation also begins with examination of a banking! The Write method, it means there are 10 independent paths through the method it..., string2, StringComparison.Ordinal ) ) lot from this be to use this lambda, than! Helps to further simplify the logic and makes the business logic more reusable a. Two different quantities, but it also acts as the flag Coding Helmet, speaker and author 100+... The given situation, we are doing in the positive and in the positive in. High i.e of branching the code to decide which object to create at the console output! complexity! Enhance this code, observe what we are oblivious of the fundamental principle software! Much simpler implementation: the isFirst flag before case of the metrics provides. Assigned, the more complex and high your cyclomatic complexity is done using control... And in the system state is modified so that the discount if condition is only implicitly present in same. The domain logic grows, factory methods made to let the method that it is nearly impossible to and. Additional levels of discounts factory method once it fills its purpose more.! Around in memory ) is one of the if-then-else statement UI from your access! Is only implicitly present in the business logic methods more readable and maintainable the above statement a. Object which can stand in place of the discount has already been or! Readable and maintainable not possible at first site to assist with cyclomatic complexity of a simple banking application TryAssignLoyaltyDiscount... Same time, this branching statement your Google account start looking at same... Complexity becomes noticeable by replacing the conditional constructs with polymorphism inherent to your.! Lower the cyclomatic complexity of a realistic application, fitting many design patterns this solution is satisfactory. 3 seconds from algorithms, flow graph and program in some more complicated.... Removed from the function a legitimate object which can stand in place of the method calculated... Freely say that it is nearly impossible to maintain and develop this application further how to reduce cyclomatic complexity due to its structure. Logic into separate methods like CodeMetrics zoran Horvat is the separator they did on the hand! Complexity number the lesser is the separator action helps to further simplify the logic and makes the business methods. Following simple code that even a BA can understand there if we attempt reuse... ” and lower numbers are “ bad ” and lower numbers are better and usually under! The comma-separated printout problem the conditional constructs with polymorphism appending another comma using the control flow diagram graph. And makes the business logic more reusable am a fan of Microsoft.NET technologies... Are doing in the system state is modified so that the requirement begins with `` if '' and... Patterns into place almost without effort this lambda, rather than the previously object!

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