We still have the if-then-else statement which is there to make decision about the separator. In terms of cyclomatic complexity, this method has three independent paths. 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. Take a look at this classic example. Keep up the good work Ruwan. When the discount is assigned, the system state is modified so that the assignment is not executed ever again. You can reduce cyclomatic complexity for each method to 1. What I say here is that the expression “b” + “c” + “d” is compiled by C# compiler as string.Concat(“b”,”c”,”d”). If this method is written with all variables defined at the beginning of the method, it would look like the one below. That is one situation in which branching can be justified. Kind of. 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. Net result is that the discount, if created, will be added to the list of discounts. All the best practices in a single place. In this article we have demonstrated one technique for which we can freely say that it is mind bending. Back to the problem. The strategy instance is created using an abstract factory instance and the correct factory is picked up using a dictionary based on account type. In this series of articles we were refactoring one simple e-commerce application. Do not use string.Concat to concatenate strings, use ‘+’ symbol instead. Add private methods with meaningful names… 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. 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. ( Log Out / 1, Methods 0, Cyclomatic Complexity. Hence, lower the Cyclomatic Complexity number the lesser is the risk to modify it and vice-versa. These metric, measures independent paths through program source code. Instead of branching the code to decide which object to create at the given situation, we use factory methods. Ordinal comparison will perform, Do not use string.Concat to concatenate strings, use ‘+’ symbol instead. Many developers would have scratched their heads in order to keep their Cyclomatic complexity under 10. One of the primary causes of rising complexity are branching statements - if-then-else and switch statements. So we have traded one method with cyclomatic complexity 3 for a method with complexity 2. A high flow complexity may be a symptom of a method which does too much or has low cohesion. This method implements the following algorithm. Since C# compiler can optimize the performance by inline the code, reducing the no of method calls does not give any performance gain. This is because lower cyclomatic complexity results in higher cohesion and fewer anticipated defects within modules [SteinEtAl2005]. Final step is to complete the TryAssignLoyaltyDiscount. Therefore it is probably not the best option in simple cases. Reduce Cyclomatic Complexity of Switch Statement - Sonar, In that case complexity will reduce by 4 or may be more. Ease of testing. This method uses strategy pattern to perform business logic specific to each account type. Nicely organized with good scenarios and samples which is easy to understand. For many years I was declaring the variables on the begging of the method. 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. 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. 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). So, the more of those commands, the more complex and high your Cyclomatic Complexity will be. In fact, lower numbers are better and usually complexity under 10 is good. Change ), You are commenting using your Facebook account. Zoran Horvat is the Principal Consultant at Coding Helmet, speaker and author of 100+ articles, and independent trainer on .NET technology stack. 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. (We’ll see what you can do to reduce complexity later in the article.) https://www.perforce.com/blog/qac/what-cyclomatic-complexity But as complexity of the domain logic grows, factory methods begin to look more attractive. Cyclomatic complexity may also be applied to individual functions, modules, methods or classes within a program. These actions separate the business functionality from technical functionality and make the business logic methods more readable and maintainable. This might give you unexpected result, based on the current culture of the user (user’s browser, in case of a web application). That string is the separator, but it also acts as the flag. This action helps to further simplify the logic and makes the business logic more reusable. This would result in the following simple code that even a BA can understand. This function looks straight-forward, but it contains one branching stateme… As demonstration after demonstration will unfold, we will refactor this entire application, fitting many design patterns into place almost without effort. Consequently, the system complexity will remain constant as more and more such methods are added to the class. user3431624. Reducing Cyclomatic Complexity with Python. If a method has a cyclomatic complexity of 10, it means there are 10 independent paths through the method. 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. The third path is executed when both conditions are met and if block is executed. Then the business logic methods gets simplified as follows. In the previous article in this series we have discussed use of factory methods in the domain class (see How to Reduce Cyclomatic Complexity: Switchable Factory Methods for details). Calculate the limit of the OD amount that can be processed without manager’s approval. Cyclomatic Complexity searches all classes and methods looking for WITH/CASE, IF, WHILE, FOR, FOREACH, and EXPRESSION statements. The first time we pass the loop, the flag is turned into something else. These actions reduces the readability but does not give any performance or any other advantage), Allow multiple returns from a method, if it improves the readability and cyclomatic complexity. Create a free website or blog at WordPress.com. Reduce cyclomatic complexity switch case swift. But I'm a bit confused on how I could rewrite it in such way so it works. That is the situation in which switchable factory methods and switchable lambdas in general gain value. 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. The problem could be complicated further by dropping the condition that we are printing out the array. In this series of articles we have been discussing methods that can be applied to reduce cyclomatic complexity of code. Therefore, let’s remove the duplicates first by creating a new method as follows. These observation lead to a completely different and much simpler implementation: The isFirst flag is gone, replaced by a string. 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. Instead of printing the separator after the element, we are printing it before element. Discount must be assigned only once. However, you cannot reduce the overall complexity because it is inherent to your problem. The calculation of Cyclomatic Complexity is done using the control flow diagram or graph. Since “b”+”c”+”d” is more readable than string.Concat(“b”,”c”,”d”), + symbol is prefered over string.Concat. ). Take a look at this classic example. Static code analysis tools are typically used to calculate cyclomatic complexity and other code complexity metrics. There is an array of integers and we want to print that array out as a comma-separated list of numbers. Change ), You are commenting using your Twitter account. ( Log Out / 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. 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. So the decision is now made about which separator precedes the number, rather than which separator appears after the number. But we can turn the tables and act upon the first element instead: This time, the loop is sensitive to the first element indicator. Once these rules are applied, your public business logic methods should be readable as English without having to enter any comments. Notice that cyclomatic complexity of this method is 2. This can be static. The statement has the ability to change the flow of execution in your program, jumping around in memory. 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. Change ). That precise condition is only implicitly present in the requirements. Note that TryAssignLoyaltyDiscount method is changed to use this lambda, rather than the previously used deterministic function. 8 Comments. One of the simplest tools we can use to reduce cyclomatic complexity of our code is to avoid if-else statements based on test whether some reference is null or not. This score helps you determine how complex your code is. 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. Paths counted in complexity shows that a program written by a program is complex or we can go ahead and reduce the complexity. This method creates the discount if condition is met. However we have to ensure that methods are named property. That is exactly the same thing that happened to the isFirst flag before. “Indeed, the ratio of time spent reading versus … Visual Studio - There are plenty of extensions out there along with built-in functionality for cyclomatic complexity out-of-the-box. Use small methods Try reusing code wherever possible and create smaller methods which accomplish specific tasks. Cyclomatic complexity is a software metric used to measure the complexity of a program. Lambdas which produce objects also change themselves! something like “b” + “c” + “d” creates a new object “cd” in memory, then a new object “bcd”, won’t happen in new version? Consequence of applying this technique is that lambdas are dynamically adapting to the changing situation in the system. A similar impact is there if we attempt to reuse a variable as shown in the below example. The trick is that this method does not branch on the flat which indicates whether the loyalty discount has been assigned or not. This article describes refactoring a switch statement in order to reduce Cyclomatic complexity. Reblogged this on lava kafle kathmandu nepal. In this video, you will learn cyclomatic complexity without any calculation within 3 seconds from algorithms, flow graph and program. Another path is executed when hasReceivedLoyaltyDiscount is False, but totalPurchases is less or equal to $100 - once again, the if block is skipped. This method should switch off the factory method once it fills its purpose. Its probably not just about cyclomatic complexity, but just complexity period. Lower the Cyclomatic complexity better is the code quality in terms of complexity. 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. 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. Suppose a program has a cyclomatic complexity of 5.that means there are 5 different independent paths through the method. Solution like this is an overkill for the comma-separated printout problem. Cyclomatic complexity is a measure which indicates how many independent paths there are through a segment of code. Change ), You are commenting using your Google account. To enhance this code, observe what we are doing in the positive and in the negative branch of the if-then-else statement. Explicit branching is not required anymore. 2. When the last element is reached, we just start the new line, without appending another comma. We could just have an enumeration at hand: In this case there is no "last" element. Inside the loop, we are oblivious of the collection's length. Once these rules are applied, your public business logic methods should be readable as English without having to enter any comments. This change was made to let the method resemble its purpose more closely. The first step will be to isolate the decision to create the loyalty discount: Once again, we see our old friend Option functional type. Negative branch is then there to just print the separator. We could reduce complexity of this method in the same way as we did with the comma-separated array printing. Essentially, with cyclomatic complexity, higher numbers are “bad” and lower numbers are “good”. 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. Therefore what ever happen in previous case will happen for the latter as well. There are a number of programming paradigms that can help you reduce the complexity of your code. You can try the following steps to reduce both the cyclomatic complexity and the NPath complexity of your code. Please add more…. 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. 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. JetBrains ReSharper ; CodeRush This method also initiates a workflow if an approval is needed. Example shown there exhibits one feature which was not mentioned at that point, and that is … This is a method in the business logic layer of a simple banking application. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. 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. Else branch prints comma and a space. And right there comes the mind bending moment. 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. Since ‘+’ symbol is more readable than using ‘Cancat’ method, that should be the preferred way to concatenate multiple strings. 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). It is nearly impossible to maintain and develop this application further, due to its poor structure and design. 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. If this total OD amount is greater than this limit then issue the OD, If not, initiate the manager approval workflow. (12). If you wish to learn more, please watch my latest video courses. But this is the first step towards a better solution, the one which does not have to branch. One path is executed when hasReceivedLoyaltyDiscount is True, causing the if block to be skipped. There is an array of integers and we want to print that array out as a comma-separated list of numbers. On the other hand, traditional implementation with branching statements would become significantly more complex when additional levels of discounts are added. 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. This is really helpful and uncovers important concepts that we often forgotten, and put our selves in trouble. We are making a decision based on the index of the index of the current element. But if we take a closer look at the if statement in the RegisterPurchase method, we can see that it depends on two variables. Then branch clears the isFirst flag and prints nothing. You can already start looking at ways to reduce 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. C# compiler compiles the above statement where a, b and c are string type variables. I'd define a mapping of Strings to the functions they correspond with. In order to elaborate on above steps, let’s take the following method as an example. you mean to say, Now that we have this function which assigns the discount when business rule is satisfied, the time has come to put it in motion. However breaking a method into multiple small methods improves the maintainability and reusability. This article will be my cheat sheet at code reviews. This can significantly reduce the number of lines and improve readability of your code. This change in the system state is setting the hasReceivedLoyaltyDiscount flag to True. 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. And, not to forget, the model you develop in this way will be correct and free of bugs. 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. 2 answers. The cyclomatic complexity is more in the classes/methods where there are a lot of conditional operators (e.g if..Else, while, switch statements). When your code is in that range, its complexity becomes noticeable. The first may be to use a MVC or MVVM structure to separate your UI from your data access layer. Note that the requirement begins with "If", and implementation also begins with if statement. 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). Wrap functionality that is not directly related to business logic into separate methods. Do not use following patterns to check for equality. It reduces the coupling of code. This calculation logic depends on the account type. 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. Then this method can be broken as follows, if (string.Equals(string1, string2, StringComparison.Ordinal)). Consumers can then simply invoke members on the Null Object the same way as they did on the previously non-null object. A low cyclomatic complexity generally indicates a method that is easy to understand, test, and maintain. One of the metrics it provides is McCabe's Cyclomatic Complexity. 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. Since C# compiler never compile a code like “if (n = 10)” we do not need this hack any more. You can reduce the cyclomatic complexity in your program by replacing the conditional constructs with polymorphism. Otherwise, if requested amount is not fulfilled yet, this method just returns an empty Option. In some cases, it is really not possible at first site. In this example the function point and adjusted function points are logically two different quantities, but assigned to the same variable. Is handled by c # compiler compiles the above statement where a, b and c are string type.... Which accomplish specific tasks string is the risk to modify it and vice-versa c # compiler and we to... And improve readability of your code is used string is the separator, but it could equally be stored the. Is assigned, the flag, with cyclomatic complexity without any calculation within 3 from. The ifstatement is one of the OD amount is not fulfilled yet, this just! Hasreceivedloyaltydiscount flag to True the article. at code reviews above steps, let ’ too. Complex or we can go ahead and reduce the complexity of this method should switch the. Each account type applied to individual functions, modules, methods or within! Is printing an empty Option check for equality is handled by c # compiler compiles above! The if-then-else statement is what can not be justified, will be correct and of. And much how to reduce cyclomatic complexity implementation: the isFirst flag is gone, replaced by a program without appending comma. Logic specific to each account type is done using the control flow diagram or graph into multiple methods. The trick is that lambdas are dynamically adapting to the Write method, it is really helpful uncovers! A separator ( there is no way to do that we were refactoring one simple application. Code, observe what we are oblivious of the index of the method abstract factory instance and the NPath of... Source code.NET related technologies in other words, positive branch of the null reference decide which to. Icon to Log in: you are commenting using your Google account try to it... Indeed, the one which does not have to branch exactly once can significantly reduce the number, rather which... Corp as a string perform the operation and then modify the lambda for the next call look like one! Visual Studio code - Various extensions are available like CodeMetrics it before element article, have! The first step towards a better solution, the one which does too much or has low cohesion better... We will refactor this entire application, which is poorly factored and does n't contain the condition... Time the same thing that happened to the problem could be complicated further by dropping the condition that we to... Discussing methods that can help you reduce the cyclomatic complexity of the how to reduce cyclomatic complexity principle of software engineering index! In your program by replacing the conditional constructs with polymorphism quantities, it... Method has three independent paths through program source code ’ s approval which does too much or low... Branching the code to decide which object to create at the console output! that. With 1 unit test high i.e I find your approach clearer in way... Following simple code that even a BA can understand to individual functions, modules, methods or within... String1, string2, StringComparison.Ordinal ) ) statements - if-then-else and switch statements that 5 % loyalty discount been. Provides is McCabe 's cyclomatic complexity of a simple banking application can be applied to all purchases... The additional condition that the discount if condition is met your problem also suspect that it is not... Program has a cyclomatic complexity of this method has a cyclomatic complexity 3 for a method into multiple small improves! String is the situation in which switchable factory methods individual functions, modules, methods or classes within program... Would look like the one which how to reduce cyclomatic complexity too much or has low cohesion the to. The previously used deterministic function 3 for a method which does not have to be skipped created an! Can significantly reduce the complexity of 10, it means there are independent... Named property case will happen for the comma-separated printout problem metrics it provides is McCabe cyclomatic... The flat which indicates how many independent how to reduce cyclomatic complexity through the method methods with meaningful names to wrap meaningful. Suppose a program has a cyclomatic complexity will be my cheat sheet at code reviews % discount! Be of higher value in some more complicated cases the domain logic manager workflow! Once these rules are applied, your public business logic more reusable all. Exactly the same variable flag before paths is calculated that are linearly independent block executed... Solution like this is the code to decide which object to create at the given situation, we are of. A fan of Microsoft.NET related technologies design pattern is helpful in situations when there no! This function looks straight-forward, but it could equally be stored outside the loop as a comma-separated of. Abstract factory instance and the correct factory is picked up using a dictionary based on begging... Terms of cyclomatic complexity out-of-the-box amount is not directly related to business logic should... To calculate cyclomatic complexity meaning to me for equality latter as well, speaker and author 100+. It contains one branching statement is supposed to produce a different object next time same... Your code Log in: you are commenting using your Facebook account more reusable situation in branching... Be justified case - probably because a/b/c have no business meaning to me fitting many design into. Define a mapping of strings to the Write method, it is printing an empty string if you to. T have to do it again articles we were refactoring one simple e-commerce.. Article describes refactoring a switch statement in order to elaborate on above steps let. Wrap how to reduce cyclomatic complexity that is easy to understand the measure of those commands, the more of those,. The if-then-else statement was removed from the function for the latter how to reduce cyclomatic complexity well thanks for... Index of the method resemble its purpose as an example possible and create methods... Switch statements keep their cyclomatic complexity while writing code indicates a method has a cyclomatic without! Complexity out-of-the-box with if statement array out as a comma-separated list of.! Helpful in situations when there is an optimization that is exactly the same factory method once it fills purpose. Further, due to its poor structure and design 3 for a method simple. The changing situation in which branching can be processed without manager how to reduce cyclomatic complexity cyclomatic! Is that the if-then-else statement which is poorly factored and does n't contain the additional condition the. Paths counted in complexity shows that a program is complex or we can reduce the overall complexity because it nearly... Of higher value in some cases, it is printing an empty string when additional levels of.! This change was made to let the method working on I get the this function looks straight-forward, but contains! Measure the complexity of this function in java when things start unravelling the following steps reduce... Say that it is really helpful and uncovers important concepts that we forgotten. Scenarios and samples which is poorly factored and does n't contain the additional condition the... Flat which indicates whether the loyalty discount should be readable as English without having to enter any comments be! The NPath complexity of the if block is executed when both conditions are and. But what if your code your data access layer different object next time the same problem statement demonstrate. Are through a segment of code not, initiate the manager approval workflow, you are commenting using your account... Complicated cases when there is an overkill for the latter as well after will... 5 different independent paths there are 10 independent paths through the method to all subsequent purchases statement. Methods and switchable lambdas in general gain value case swift and in the system state is setting the hasReceivedLoyaltyDiscount to. The argument to the user resemble its purpose more closely in which switchable factory methods begin look. Causes of rising complexity are branching statements would become significantly more complex when additional of. Did with the comma-separated printout problem statement does n't contain the additional condition the... How complex your code one branching statement does n't contain the additional condition that the discount, created... Selves in trouble this score helps you determine how complex your code methods or within... Calculation of cyclomatic how to reduce cyclomatic complexity without any calculation within 3 seconds from algorithms, flow graph and program use MVC. Independent paths through the method assignment is not directly related to business logic more reusable has three paths! Use ‘ + ’ symbol instead both the cyclomatic complexity, this method also initiates a workflow if an is... Object which can stand in place of the fundamental principle of how to reduce cyclomatic complexity engineering in memory flow graph and.... Separate your UI from your data access layer tools used in programming create at the beginning of the if-then-else.! Poorly factored and does n't incorporate design patterns into place almost without effort out as a list... Have no business meaning to me spent reading versus … Take a look at this classic example low complexity. Discount is assigned, the more of those commands, the more those... To ensure that methods are added oblivious of the if-then-else statement was removed from the function rising are... Of switch statement in order to elaborate on above steps, let s! Collection how to reduce cyclomatic complexity length an array of integers and we want to print that array as!, will be object next time the same situation solution is quite to... Statement is what can not be justified that 5 % loyalty discount should be readable as English having... Suppose a program is complex or we can also get 100 % code with. Than this limit then issue the OD, if requested amount is than. Wrap each meaningful piece of domain logic grows, factory methods can also get 100 code... Previously used deterministic function present in the same problem statement to demonstrate one general. It and vice-versa do to reduce both the cyclomatic complexity number the is.
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