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🛁 Clean Code concepts and tools adapted for .NET
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thangchung/clean-code-dotnet
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- Clean Code concepts adapted for .NET/.NET Core
- Table of Contents
- Introduction
- Clean Code .NET
- Other Clean Code Resources
- Contributors
- Backers
- Sponsors
- License
Software engineering principles, from Robert C. Martin's bookClean Code, adapted for .NET/.NET Core. This is not a style guide. It's a guide to producing readable, reusable, and refactorable software in .NET/.NET Core.
Not every principle herein has to be strictly followed, and even fewer will be universally agreed upon. These are guidelines and nothing more, but they are ones codified over many years of collective experience by the authors ofClean Code.
Inspired fromclean-code-javascript andclean-code-php lists.
Avoid using bad names
A good name allows the code to be used by many developers. The name should reflect what it does and give context.Bad:
intd;
Good:
intdaySinceModification;
Avoid Misleading Names
Name the variable to reflect what it is used for.
Bad:
vardataFromDb=db.GetFromService().ToList();
Good:
varlistOfEmployee=_employeeService.GetEmployees().ToList();
Avoid Hungarian notation
Hungarian Notation restates the type which is already present in the declaration. This is pointless since modern IDEs will identify the type.
Bad:
intiCounter;stringstrFullName;DateTimedModifiedDate;
Good:
intcounter;stringfullName;DateTimemodifiedDate;
Hungarian Notation should also not be used in paramaters.
Bad:
publicboolIsShopOpen(stringpDay,intpAmount){// some logic}
Good:
publicboolIsShopOpen(stringday,intamount){// some logic}
Use consistent capitalization
Capitalization tells you a lot about your variables,functions, etc. These rules are subjective, so your team can choose whateverthey want. The point is, no matter what you all choose, just be consistent.
Bad:
constintDAYS_IN_WEEK=7;constintdaysInMonth=30;varsongs=newList<string>{'Back In Black','Stairway to Heaven','Hey Jude'};varArtists=newList<string>{'ACDC','Led Zeppelin','The Beatles'};boolEraseDatabase(){}boolRestore_database(){}classanimal{}classAlpaca{}
Good:
constintDaysInWeek=7;constintDaysInMonth=30;varsongs=newList<string>{'Back In Black','Stairway to Heaven','Hey Jude'};varartists=newList<string>{'ACDC','Led Zeppelin','The Beatles'};boolEraseDatabase(){}boolRestoreDatabase(){}classAnimal{}classAlpaca{}
Use pronounceable names
It will take time to investigate the meaning of the variables and functions when they are not pronounceable.
Bad:
publicclassEmployee{publicDatetimesWorkDate{get;set;}// what the heck is thispublicDatetimemodTime{get;set;}// same here}
Good:
publicclassEmployee{publicDatetimeStartWorkingDate{get;set;}publicDatetimeModificationTime{get;set;}}
Use Camelcase notation
UseCamelcase Notation for variable and method paramaters.
Bad:
varemployeephone;publicdoubleCalculateSalary(intworkingdays,intworkinghours){// some logic}
Good:
varemployeePhone;publicdoubleCalculateSalary(intworkingDays,intworkingHours){// some logic}
Use domain name
People who read your code are also programmers. Naming things right will help everyone be on the same page. We don't want to take time to explain to everyone what a variable or function is for.
Good
publicclassSingleObject{// create an object of SingleObjectprivatestaticSingleObject_instance=newSingleObject();// make the constructor private so that this class cannot be instantiatedprivateSingleObject(){}// get the only object availablepublicstaticSingleObjectGetInstance(){return_instance;}publicstringShowMessage(){return"Hello World!";}}publicstaticvoidmain(String[]args){// illegal construct// var object = new SingleObject();// Get the only object availablevarsingletonObject=SingleObject.GetInstance();// show the messagesingletonObject.ShowMessage();}
Avoid nesting too deeply and return early
Too many if else statements can make the code hard to follow.Explicit is better than implicit.
Bad:
publicboolIsShopOpen(stringday){if(!string.IsNullOrEmpty(day)){day=day.ToLower();if(day=="friday"){returntrue;}elseif(day=="saturday"){returntrue;}elseif(day=="sunday"){returntrue;}else{returnfalse;}}else{returnfalse;}}
Good:
publicboolIsShopOpen(stringday){if(string.IsNullOrEmpty(day)){returnfalse;}varopeningDays=new[]{"friday","saturday","sunday"};returnopeningDays.Any(d=>d==day.ToLower());}
Bad:
publiclongFibonacci(intn){if(n<50){if(n!=0){if(n!=1){returnFibonacci(n-1)+Fibonacci(n-2);}else{return1;}}else{return0;}}else{thrownewSystem.Exception("Not supported");}}
Good:
publiclongFibonacci(intn){if(n==0){return0;}if(n==1){return1;}if(n>50){thrownewSystem.Exception("Not supported");}returnFibonacci(n-1)+Fibonacci(n-2);}
Avoid mental mapping
Don’t force the reader of your code to translate what the variable means.Explicit is better than implicit.
Bad:
varl=new[]{"Austin","New York","San Francisco"};for(vari=0;i<l.Count();i++){varli=l[i];DoStuff();DoSomeOtherStuff();// ...// ...// ...// Wait, what is `li` for again?Dispatch(li);}
Good:
varlocations=new[]{"Austin","New York","San Francisco"};foreach(varlocationinlocations){DoStuff();DoSomeOtherStuff();// ...// ...// ...Dispatch(location);}
Avoid magic string
Magic strings are string values that are specified directly within application code that have an impact on the application’s behavior. Frequently, such strings will end up being duplicated within the system, and since they cannot automatically be updated using refactoring tools, they become a common source of bugs when changes are made to some strings but not others.
Bad
if(userRole=="Admin"){// logic in here}
Good
conststringADMIN_ROLE="Admin"if(userRole==ADMIN_ROLE){// logic in here}
Using this we only have to change in centralize place and others will adapt it.
Don't add unneeded context
If your class/object name tells you something, don't repeat that in your variable name.
Bad:
publicclassCar{publicstringCarMake{get;set;}publicstringCarModel{get;set;}publicstringCarColor{get;set;}//...}
Good:
publicclassCar{publicstringMake{get;set;}publicstringModel{get;set;}publicstringColor{get;set;}//...}
Use meaningful and pronounceable variable names
Bad:
varymdstr=DateTime.UtcNow.ToString("MMMM dd, yyyy");
Good:
varcurrentDate=DateTime.UtcNow.ToString("MMMM dd, yyyy");
Use the same vocabulary for the same type of variable
Bad:
GetUserInfo();GetUserData();GetUserRecord();GetUserProfile();
Good:
GetUser();
Use searchable names (part 1)
We will read more code than we will ever write. It's important that the code we do write is readable and searchable. Bynot naming variables that end up being meaningful for understanding our program, we hurt our readers. Make your names searchable.
Bad:
// What the heck is data for?vardata=new{Name="John",Age=42};varstream1=newMemoryStream();varser1=newDataContractJsonSerializer(typeof(object));ser1.WriteObject(stream1,data);stream1.Position=0;varsr1=newStreamReader(stream1);Console.Write("JSON form of Data object: ");Console.WriteLine(sr1.ReadToEnd());
Good:
varperson=newPerson{Name="John",Age=42};varstream2=newMemoryStream();varser2=newDataContractJsonSerializer(typeof(Person));ser2.WriteObject(stream2,data);stream2.Position=0;varsr2=newStreamReader(stream2);Console.Write("JSON form of Data object: ");Console.WriteLine(sr2.ReadToEnd());
Use searchable names (part 2)
Bad:
vardata=new{Name="John",Age=42,PersonAccess=4};// What the heck is 4 for?if(data.PersonAccess==4){// do edit ...}
Good:
publicenumPersonAccess:int{ACCESS_READ=1,ACCESS_CREATE=2,ACCESS_UPDATE=4,ACCESS_DELETE=8}varperson=newPerson{Name="John",Age=42,PersonAccess=PersonAccess.ACCESS_CREATE};if(person.PersonAccess==PersonAccess.ACCESS_UPDATE){// do edit ...}
Use explanatory variables
Bad:
conststringAddress="One Infinite Loop, Cupertino 95014";varcityZipCodeRegex=@"/^[^,\]+[,\\s]+(.+?)\s*(\d{5})?$/";varmatches=Regex.Matches(Address,cityZipCodeRegex);if(matches[0].Success==true&&matches[1].Success==true){SaveCityZipCode(matches[0].Value,matches[1].Value);}
Good:
Decrease dependence on regex by naming subpatterns.
conststringAddress="One Infinite Loop, Cupertino 95014";varcityZipCodeWithGroupRegex=@"/^[^,\]+[,\\s]+(?<city>.+?)\s*(?<zipCode>\d{5})?$/";varmatchesWithGroup=Regex.Match(Address,cityZipCodeWithGroupRegex);varcityGroup=matchesWithGroup.Groups["city"];varzipCodeGroup=matchesWithGroup.Groups["zipCode"];if(cityGroup.Success==true&&zipCodeGroup.Success==true){SaveCityZipCode(cityGroup.Value,zipCodeGroup.Value);}
Use default arguments instead of short circuiting or conditionals
Not good:
This is not good becausebreweryName can beNULL.
This opinion is more understandable than the previous version, but it better controls the value of the variable.
publicvoidCreateMicrobrewery(stringname=null){varbreweryName=!string.IsNullOrEmpty(name)?name:"Hipster Brew Co.";// ...}
Good:
publicvoidCreateMicrobrewery(stringbreweryName="Hipster Brew Co."){// ...}
Avoid side effects
A function produces a side effect if it does anything other than take a value in and return another value or values. A side effect could be writing to a file, modifying some global variable, or accidentally wiring all your money to a stranger.
Now, you do need to have side effects in a program on occasion. Like the previous example, you might need to write to a file. What you want to do is to centralize where you are doing this. Don't have several functions and classes that write to a particular file. Have one service that does it. One and only one.
The main point is to avoid common pitfalls like sharing state between objects without any structure, using mutable data types that can be written to by anything, and not centralizing where your side effects occur. If you can do this, you will be happierthan the vast majority of other programmers.
Bad:
// Global variable referenced by following function.// If we had another function that used this name, now it'd be an array and it could break it.varname="Ryan McDermott";publicvoidSplitAndEnrichFullName(){vartemp=name.Split(" ");name=$"His first name is{temp[0]}, and his last name is{temp[1]}";// side effect}SplitAndEnrichFullName();Console.WriteLine(name);// His first name is Ryan, and his last name is McDermott
Good:
publicstringSplitAndEnrichFullName(stringname){vartemp=name.Split(" ");return$"His first name is{temp[0]}, and his last name is{temp[1]}";}varname="Ryan McDermott";varfullName=SplitAndEnrichFullName(name);Console.WriteLine(name);// Ryan McDermottConsole.WriteLine(fullName);// His first name is Ryan, and his last name is McDermott
Avoid negative conditionals
Bad:
publicboolIsDOMNodeNotPresent(stringnode){// ...}if(!IsDOMNodeNotPresent(node)){// ...}
Good:
publicboolIsDOMNodePresent(stringnode){// ...}if(IsDOMNodePresent(node)){// ...}
Avoid conditionals
This seems like an impossible task. Upon first hearing this, most people say, "how am I supposed to do anything without anif statement?" The answer is that you can use polymorphism to achieve the same task in many cases. The second question is usually, "well that's great but why would I want to do that?" The answer is a previous clean code concept we learned: a function should only doone thing. When you have classes and functions that haveif statements, you are telling your user that your function does more than one thing. Remember, just do one thing.
Bad:
classAirplane{// ...publicdoubleGetCruisingAltitude(){switch(_type){case'777':returnGetMaxAltitude()-GetPassengerCount();case'Air Force One':returnGetMaxAltitude();case'Cessna':returnGetMaxAltitude()-GetFuelExpenditure();}}}
Good:
interfaceIAirplane{// ...doubleGetCruisingAltitude();}classBoeing777:IAirplane{// ...publicdoubleGetCruisingAltitude(){returnGetMaxAltitude()-GetPassengerCount();}}classAirForceOne:IAirplane{// ...publicdoubleGetCruisingAltitude(){returnGetMaxAltitude();}}classCessna:IAirplane{// ...publicdoubleGetCruisingAltitude(){returnGetMaxAltitude()-GetFuelExpenditure();}}
Avoid type-checking (part 1)
Bad:
publicPathTravelToTexas(objectvehicle){if(vehicle.GetType()==typeof(Bicycle)){(vehicleasBicycle).PeddleTo(newLocation("texas"));}elseif(vehicle.GetType()==typeof(Car)){(vehicleasCar).DriveTo(newLocation("texas"));}}
Good:
publicPathTravelToTexas(Travelervehicle){vehicle.TravelTo(newLocation("texas"));}
or
// pattern matchingpublicPathTravelToTexas(objectvehicle){if(vehicleisBicyclebicycle){bicycle.PeddleTo(newLocation("texas"));}elseif(vehicleisCarcar){car.DriveTo(newLocation("texas"));}}
Avoid type-checking (part 2)
Bad:
publicintCombine(dynamicval1,dynamicval2){intvalue;if(!int.TryParse(val1,outvalue)||!int.TryParse(val2,outvalue)){thrownewException('Must be of type Number');}returnval1+val2;}
Good:
publicintCombine(intval1,intval2){returnval1+val2;}
Avoid flags in method parameters
A flag indicates that the method has more than one responsibility. It is best if the method only has a single responsibility. Split the method into two if a boolean parameter adds multiple responsibilities to the method.
Bad:
publicvoidCreateFile(stringname,booltemp=false){if(temp){Touch("./temp/"+name);}else{Touch(name);}}
Good:
publicvoidCreateFile(stringname){Touch(name);}publicvoidCreateTempFile(stringname){Touch("./temp/"+name);}
Don't write to global functions
Polluting globals is a bad practice in many languages because you could clash with another library and the user of your API would be none-the-wiser until they get an exception in production. Let's think about an example: what if you wanted to have configuration array.You could write global function likeConfig(), but it could clash with another library that tried to do the same thing.
Bad:
publicDictionary<string,string>Config(){returnnewDictionary<string,string>(){["foo"]="bar"};}
Good:
classConfiguration{privateDictionary<string,string>_configuration;publicConfiguration(Dictionary<string,string>configuration){_configuration=configuration;}publicstring[]Get(stringkey){return_configuration.ContainsKey(key)?_configuration[key]:null;}}
Load configuration and create instance ofConfiguration class
varconfiguration=newConfiguration(newDictionary<string,string>(){["foo"]="bar"});
And now you must use instance ofConfiguration in your application.
Don't use a Singleton pattern
Singleton is ananti-pattern. Paraphrased from Brian Button:
- They are generally used as aglobal instance, why is that so bad? Becauseyou hide the dependencies of your application in your code, instead of exposing them through the interfaces. Making something global to avoid passing it around is acode smell.
- They violate thesingle responsibility principle: by virtue of the fact thatthey control their own creation and lifecycle.
- They inherently cause code to be tightlycoupled. This makes faking them out undertest rather difficult in many cases.
- They carry state around for the lifetime of the application. Another hit to testing sinceyou can end up with a situation where tests need to be ordered which is a big no for unit tests. Why? Because each unit test should be independent from the other.
There is also very good thoughts byMisko Hevery about theroot of problem.
Bad:
classDBConnection{privatestaticDBConnection_instance;privateDBConnection(){// ...}publicstaticGetInstance(){if(_instance==null){_instance=newDBConnection();}return_instance;}// ...}varsingleton=DBConnection.GetInstance();
Good:
classDBConnection{publicDBConnection(IOptions<DbConnectionOption>options){// ...}// ...}
Create instance ofDBConnection class and configure it withOption pattern.
varoptions=<resolvefrom IOC>;varconnection=newDBConnection(options);
And now you must use instance ofDBConnection in your application.
Function arguments (2 or fewer ideally)
Limiting the amount of function parameters is incredibly important because it makes testing your function easier. Having more than three leads to a combinatorial explosion where you have to test tons of different cases with each separate argument.
Zero arguments is the ideal case. One or two arguments is ok, and three should be avoided. Anything more than that should be consolidated. Usually, if you have more than two arguments then your function is trying to do too much. In cases where it's not, most of the time a higher-level object will suffice as an argument.
Bad:
publicvoidCreateMenu(stringtitle,stringbody,stringbuttonText,boolcancellable){// ...}
Good:
publicclassMenuConfig{publicstringTitle{get;set;}publicstringBody{get;set;}publicstringButtonText{get;set;}publicboolCancellable{get;set;}}varconfig=newMenuConfig{Title="Foo",Body="Bar",ButtonText="Baz",Cancellable=true};publicvoidCreateMenu(MenuConfigconfig){// ...}
Functions should do one thing
This is by far the most important rule in software engineering. When functions do more than one thing, they are harder to compose, test, and reason about. When you can isolate a function to just one action, they can be refactored easily and your code will read muchcleaner. If you take nothing else away from this guide other than this, you'll be ahead of many developers.
Bad:
publicvoidSendEmailToListOfClients(string[]clients){foreach(varclientinclients){varclientRecord=db.Find(client);if(clientRecord.IsActive()){Email(client);}}}
Good:
publicvoidSendEmailToListOfClients(string[]clients){varactiveClients=GetActiveClients(clients);// Do some logic}publicList<Client>GetActiveClients(string[]clients){returndb.Find(clients).Where(s=>s.Status=="Active");}
Function names should say what they do
Bad:
publicclassEmail{//...publicvoidHandle(){SendMail(this._to,this._subject,this._body);}}varmessage=newEmail(...);// What is this? A handle for the message? Are we writing to a file now?message.Handle();
Good:
publicclassEmail{//...publicvoidSend(){SendMail(this._to,this._subject,this._body);}}varmessage=newEmail(...);// Clear and obviousmessage.Send();
Functions should only be one level of abstraction
Not finished yet
When you have more than one level of abstraction your function is usually doing too much. Splitting up functions leads to reusability and easier testing.
Bad:
publicstringParseBetterJSAlternative(stringcode){varregexes=[// ...];varstatements=explode(" ",code);vartokens=newstring[]{};foreach(varregexinregexes){foreach(varstatementinstatements){// ...}}varast=newstring[]{};foreach(vartokenintokens){// lex...}foreach(varnodeinast){// parse...}}
Bad too:
We have carried out some of the functionality, but theParseBetterJSAlternative() function is still very complex and not testable.
publicstringTokenize(stringcode){varregexes=newstring[]{// ...};varstatements=explode(" ",code);vartokens=newstring[]{};foreach(varregexinregexes){foreach(varstatementinstatements){tokens[]=/* ... */;}}returntokens;}publicstringLexer(string[]tokens){varast=newstring[]{};foreach(vartokenintokens){ast[]=/* ... */;}returnast;}publicstringParseBetterJSAlternative(stringcode){vartokens=Tokenize(code);varast=Lexer(tokens);foreach(varnodeinast){// parse...}}
Good:
The best solution is move out the dependencies ofParseBetterJSAlternative() function.
classTokenizer{publicstringTokenize(stringcode){varregexes=newstring[]{// ...};varstatements=explode(" ",code);vartokens=newstring[]{};foreach(varregexinregexes){foreach(varstatementinstatements){tokens[]=/* ... */;}}returntokens;}}classLexer{publicstringLexify(string[]tokens){varast=new[]{};foreach(vartokenintokens){ast[]=/* ... */;}returnast;}}classBetterJSAlternative{privatestring_tokenizer;privatestring_lexer;publicBetterJSAlternative(Tokenizer tokenizer,Lexer lexer){_tokenizer=tokenizer;_lexer=lexer;}publicstringParse(stringcode){vartokens=_tokenizer.Tokenize(code);varast=_lexer.Lexify(tokens);foreach(varnodeinast){// parse...}}}
Function callers and callees should be close
If a function calls another, keep those functions vertically close in the source file. Ideally, keep the caller right above the callee. We tend to read code from top-to-bottom, like a newspaper. Because of this, make your code read that way.
Bad:
classPerformanceReview{privatereadonlyEmployee_employee;publicPerformanceReview(Employeeemployee){_employee=employee;}privateIEnumerable<PeersData>LookupPeers(){returndb.lookup(_employee,'peers');}privateManagerDataLookupManager(){returndb.lookup(_employee,'manager');}privateIEnumerable<PeerReviews>GetPeerReviews(){varpeers=LookupPeers();// ...}publicPerfReviewDataPerfReview(){GetPeerReviews();GetManagerReview();GetSelfReview();}publicManagerDataGetManagerReview(){varmanager=LookupManager();}publicEmployeeDataGetSelfReview(){// ...}}varreview=newPerformanceReview(employee);review.PerfReview();
Good:
classPerformanceReview{privatereadonlyEmployee_employee;publicPerformanceReview(Employeeemployee){_employee=employee;}publicPerfReviewDataPerfReview(){GetPeerReviews();GetManagerReview();GetSelfReview();}privateIEnumerable<PeerReviews>GetPeerReviews(){varpeers=LookupPeers();// ...}privateIEnumerable<PeersData>LookupPeers(){returndb.lookup(_employee,'peers');}privateManagerDataGetManagerReview(){varmanager=LookupManager();returnmanager;}privateManagerDataLookupManager(){returndb.lookup(_employee,'manager');}privateEmployeeDataGetSelfReview(){// ...}}varreview=newPerformanceReview(employee);review.PerfReview();
Encapsulate conditionals
Bad:
if(article.state=="published"){// ...}
Good:
if(article.IsPublished()){// ...}
Remove dead code
Dead code is just as bad as duplicate code. There's no reason to keep it in your codebase. If it's not being called, get rid of it! It will still be safe in your version history if you still need it.
Bad:
publicvoidOldRequestModule(stringurl){// ...}publicvoidNewRequestModule(stringurl){// ...}varrequest=NewRequestModule(requestUrl);InventoryTracker("apples",request,"www.inventory-awesome.io");
Good:
publicvoidRequestModule(stringurl){// ...}varrequest=RequestModule(requestUrl);InventoryTracker("apples",request,"www.inventory-awesome.io");
Use getters and setters
In C# / VB.NET you can setpublic,protected andprivate keywords for methods.Using it, you can control properties modification on an object.
- When you want to do more beyond getting an object property, you don't have to look up and change every accessor in your codebase.
- Makes adding validation simple when doing a
set. - Encapsulates the internal representation.
- Easy to add logging and error handling when getting and setting.
- Inheriting this class, you can override default functionality.
- You can lazy load your object's properties, let's say getting it from a server.
Additionally, this is part of Open/Closed principle, from object-oriented design principles.
Bad:
classBankAccount{publicdoubleBalance=1000;}varbankAccount=newBankAccount();// Fake buy shoes...bankAccount.Balance-=100;
Good:
classBankAccount{privatedouble_balance=0.0D;pubicdouble Balance{get{return_balance;}}publicBankAccount(balance=1000){_balance=balance;}publicvoidWithdrawBalance(intamount){if(amount>_balance){thrownewException('Amount greater than available balance.');}_balance-=amount;}publicvoidDepositBalance(intamount){_balance+=amount;}}varbankAccount=newBankAccount();// Buy shoes...bankAccount.WithdrawBalance(price);// Get balancebalance=bankAccount.Balance;
Make objects have private/protected members
Bad:
classEmployee{publicstringName{get;set;}publicEmployee(stringname){Name=name;}}varemployee=newEmployee("John Doe");Console.WriteLine(employee.Name);// Employee name: John Doe
Good:
classEmployee{publicstringName{get;}publicEmployee(stringname){Name=name;}}varemployee=newEmployee("John Doe");Console.WriteLine(employee.Name);// Employee name: John Doe
Use method chaining
This pattern is very useful and commonly used in many libraries. It allows your code to be expressive, and less verbose.For that reason, use method chaining and take a look at how clean your code will be.
Good:
publicstaticclassListExtensions{publicstaticList<T>FluentAdd<T>(thisList<T>list,Titem){list.Add(item);returnlist;}publicstaticList<T>FluentClear<T>(thisList<T>list){list.Clear();returnlist;}publicstaticList<T>FluentForEach<T>(thisList<T>list,Action<T>action){list.ForEach(action);returnlist;}publicstaticList<T>FluentInsert<T>(thisList<T>list,intindex,Titem){list.Insert(index,item);returnlist;}publicstaticList<T>FluentRemoveAt<T>(thisList<T>list,intindex){list.RemoveAt(index);returnlist;}publicstaticList<T>FluentReverse<T>(thisList<T>list){list.Reverse();returnlist;}}internalstaticvoidListFluentExtensions(){varlist=newList<int>(){1,2,3,4,5}.FluentAdd(1).FluentInsert(0,0).FluentRemoveAt(1).FluentReverse().FluentForEach(value=>value.WriteLine()).FluentClear();}
Prefer composition over inheritance
As stated famously inDesign Patterns by the Gang of Four,you should prefer composition over inheritance where you can. There are lots of good reasons to use inheritance and lots of good reasons to use composition.
The main point for this maxim is that if your mind instinctively goes for inheritance, try to think if composition could model your problem better. In some cases it can.
You might be wondering then, "when should I use inheritance?" Itdepends on your problem at hand, but this is a decent list of when inheritance makes more sense than composition:
- Your inheritance represents an "is-a" relationship and not a "has-a" relationship (Human->Animal vs. User->UserDetails).
- You can reuse code from the base classes (Humans can move like all animals).
- You want to make global changes to derived classes by changing a base class (Change the caloric expenditure of all animals when they move).
Bad:
classEmployee{privatestringName{get;set;}privatestringEmail{get;set;}publicEmployee(stringname,stringemail){Name=name;Email=email;}// ...}// Bad because Employees "have" tax data.// EmployeeTaxData is not a type of EmployeeclassEmployeeTaxData:Employee{privatestringName{get;}privatestringEmail{get;}publicEmployeeTaxData(stringname,stringemail,stringssn,stringsalary){// ...}// ...}
Good:
classEmployeeTaxData{publicstringSsn{get;}publicstringSalary{get;}publicEmployeeTaxData(stringssn,stringsalary){Ssn=ssn;Salary=salary;}// ...}classEmployee{publicstringName{get;}publicstringEmail{get;}publicEmployeeTaxDataTaxData{get;}publicEmployee(stringname,stringemail){Name=name;Email=email;}publicvoidSetTax(stringssn,doublesalary){TaxData=newEmployeeTaxData(ssn,salary);}// ...}
What is SOLID?
SOLID is the mnemonic acronym introduced by Michael Feathers for the first five principles named by Robert Martin, which meant five basic principles of object-oriented programming and design.
Single Responsibility Principle (SRP)
As stated in Clean Code, "There should never be more than one reason for a class to change". It's tempting to jam-pack a class with a lot of functionality, like when you can only take one suitcase on your flight. The issue with this is that your class won't be conceptually cohesive and it will give it many reasons to change. Minimizing the amount of times you need to change a class is important.
It's important because if too much functionality is in one class and you modify a piece of it, it can be difficult to understand how that will affect other dependent modules in your codebase.
Bad:
classUserSettings{privateUserUser;publicUserSettings(Useruser){User=user;}publicvoidChangeSettings(Settingssettings){if(verifyCredentials()){// ...}}privateboolVerifyCredentials(){// ...}}
Good:
classUserAuth{privateUserUser;publicUserAuth(Useruser){User=user;}publicboolVerifyCredentials(){// ...}}classUserSettings{privateUserUser;privateUserAuthAuth;publicUserSettings(Useruser){User=user;Auth=newUserAuth(user);}publicvoidChangeSettings(Settingssettings){if(Auth.VerifyCredentials()){// ...}}}
Open/Closed Principle (OCP)
As stated by Bertrand Meyer, "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification." What does that mean though? This principle basically states that you should allow users to add new functionalities without changing existing code.
Bad:
abstractclassAdapterBase{protectedstringName;publicstringGetName(){returnName;}}classAjaxAdapter:AdapterBase{publicAjaxAdapter(){Name="ajaxAdapter";}}classNodeAdapter:AdapterBase{publicNodeAdapter(){Name="nodeAdapter";}}classHttpRequester:AdapterBase{privatereadonlyAdapterBaseAdapter;publicHttpRequester(AdapterBaseadapter){Adapter=adapter;}publicboolFetch(stringurl){varadapterName=Adapter.GetName();if(adapterName=="ajaxAdapter"){returnMakeAjaxCall(url);}elseif(adapterName=="httpNodeAdapter"){returnMakeHttpCall(url);}}privateboolMakeAjaxCall(stringurl){// request and return promise}privateboolMakeHttpCall(stringurl){// request and return promise}}
Good:
interfaceIAdapter{boolRequest(stringurl);}classAjaxAdapter:IAdapter{publicboolRequest(stringurl){// request and return promise}}classNodeAdapter:IAdapter{publicboolRequest(stringurl){// request and return promise}}classHttpRequester{privatereadonlyIAdapterAdapter;publicHttpRequester(IAdapteradapter){Adapter=adapter;}publicboolFetch(stringurl){returnAdapter.Request(url);}}
Liskov Substitution Principle (LSP)
This is a scary term for a very simple concept. It's formally defined as "If S is a subtype of T, then objects of type T may be replaced with objects of type S (i.e., objects of type S may substitute objects of type T) without altering any of the desirable properties of that program (correctness, task performed,etc.)." That's an even scarier definition.
The best explanation for this is if you have a parent class and a child class, then the base class and child class can be used interchangeably without getting incorrect results. This might still be confusing, so let's take a look at the classic Square-Rectangle example. Mathematically, a square is a rectangle, but if you model it using the "is-a" relationship via inheritance, you quicklyget into trouble.
Bad:
classRectangle{protecteddoubleWidth=0;protecteddoubleHeight=0;publicDrawableRender(doublearea){// ...}publicvoidSetWidth(doublewidth){Width=width;}publicvoidSetHeight(doubleheight){Height=height;}publicdoubleGetArea(){returnWidth*Height;}}classSquare:Rectangle{publicdoubleSetWidth(doublewidth){Width=Height=width;}publicdoubleSetHeight(doubleheight){Width=Height=height;}}DrawableRenderLargeRectangles(Rectanglerectangles){foreach(rectangleinrectangles){rectangle.SetWidth(4);rectangle.SetHeight(5);vararea=rectangle.GetArea();// BAD: Will return 25 for Square. Should be 20.rectangle.Render(area);}}varrectangles=new[]{newRectangle(),newRectangle(),newSquare()};RenderLargeRectangles(rectangles);
Good:
abstractclassShapeBase{protecteddoubleWidth=0;protecteddoubleHeight=0;abstractpublicdoubleGetArea();publicDrawableRender(doublearea){// ...}}classRectangle:ShapeBase{publicvoidSetWidth(doublewidth){Width=width;}publicvoidSetHeight(doubleheight){Height=height;}publicdoubleGetArea(){returnWidth*Height;}}classSquare:ShapeBase{privatedoubleLength=0;publicdoubleSetLength(doublelength){Length=length;}publicdoubleGetArea(){returnMath.Pow(Length,2);}}DrawableRenderLargeRectangles(Rectanglerectangles){foreach(rectangleinrectangles){if(rectangleisSquare){rectangle.SetLength(5);}elseif(rectangleisRectangle){rectangle.SetWidth(4);rectangle.SetHeight(5);}vararea=rectangle.GetArea();rectangle.Render(area);}}varshapes=new[]{newRectangle(),newRectangle(),newSquare()};RenderLargeRectangles(shapes);
Interface Segregation Principle (ISP)
ISP states that "Clients should not be forced to depend upon interfaces that they do not use."
A good example to look at that demonstrates this principle is forclasses that require large settings objects. Not requiring clients to setup huge amounts of options is beneficial, because most of the time they won't need all of the settings. Making them optional helps prevent having a "fat interface".
Bad:
publicinterfaceIEmployee{voidWork();voidEat();}publicclassHuman:IEmployee{publicvoidWork(){// ....working}publicvoidEat(){// ...... eating in lunch break}}publicclassRobot:IEmployee{publicvoidWork(){//.... working much more}publicvoidEat(){//.... robot can't eat, but it must implement this method}}
Good:
Not every worker is an employee, but every employee is an worker.
publicinterfaceIWorkable{voidWork();}publicinterfaceIFeedable{voidEat();}publicinterfaceIEmployee:IFeedable,IWorkable{}publicclassHuman:IEmployee{publicvoidWork(){// ....working}publicvoidEat(){//.... eating in lunch break}}// robot can only workpublicclassRobot:IWorkable{publicvoidWork(){// ....working}}
Dependency Inversion Principle (DIP)
This principle states two essential things:
- High-level modules should not depend on low-level modules. Both should depend on abstractions.
- Abstractions should not depend upon details. Details should depend on abstractions.
This can be hard to understand at first, but if you've worked with .NET/.NET Core framework, you've seen an implementation of this principle in the form ofDependency Injection (DI). While they are not identical concepts, DIP keeps high-level modules from knowing the details of its low-level modules and setting them up.It can accomplish this through DI. A huge benefit of this is that it reduces the coupling between modules. Coupling is a very bad development pattern because it makes your code hard to refactor.
Bad:
publicabstractclassEmployeeBase{protectedvirtualvoidWork(){// ....working}}publicclassHuman:EmployeeBase{publicoverridevoidWork(){//.... working much more}}publicclassRobot:EmployeeBase{publicoverridevoidWork(){//.... working much, much more}}publicclassManager{privatereadonlyRobot_robot;privatereadonlyHuman_human;publicManager(Robotrobot,Humanhuman){_robot=robot;_human=human;}publicvoidManage(){_robot.Work();_human.Work();}}
Good:
publicinterfaceIEmployee{voidWork();}publicclassHuman:IEmployee{publicvoidWork(){// ....working}}publicclassRobot:IEmployee{publicvoidWork(){//.... working much more}}publicclassManager{privatereadonlyIEnumerable<IEmployee>_employees;publicManager(IEnumerable<IEmployee>employees){_employees=employees;}publicvoidManage(){foreach(varemployeein_employees){_employee.Work();}}}
Don’t repeat yourself (DRY)
Try to observe theDRY principle.
Do your absolute best to avoid duplicate code. Duplicate code is bad because it means that there's more than one place to alter something if you need to change some logic.
Imagine if you run a restaurant and you keep track of your inventory: all your tomatoes, onions, garlic, spices, etc. If you have multiple lists that you keep this on, then all have to be updated when you serve a dish with tomatoes in them. If you only have one list, there's only one place to update!
Oftentimes you have duplicate code because you have two or more slightly different things, that share a lot in common, but their differences force you to have two or more separate functions that do much of the same things. Removing duplicate code means creating an abstraction that can handle this set of different things with just one function/module/class.
Getting the abstraction right is critical, that's why you should follow the SOLID principles laid out in theClasses section. Bad abstractions can be worse than duplicate code, so be careful! Having said this, if you can make a good abstraction, do it! Don't repeat yourself, otherwise you'll find yourself updating multiple places anytime you want to change one thing.
Bad:
publicList<EmployeeData>ShowDeveloperList(Developersdevelopers){foreach(vardevelopersindeveloper){varexpectedSalary=developer.CalculateExpectedSalary();varexperience=developer.GetExperience();vargithubLink=developer.GetGithubLink();vardata=new[]{expectedSalary,experience,githubLink};Render(data);}}publicList<ManagerData>ShowManagerList(Managermanagers){foreach(varmanagerinmanagers){varexpectedSalary=manager.CalculateExpectedSalary();varexperience=manager.GetExperience();vargithubLink=manager.GetGithubLink();vardata=new[]{expectedSalary,experience,githubLink};render(data);}}
Good:
publicList<EmployeeData>ShowList(Employeeemployees){foreach(varemployeeinemployees){varexpectedSalary=employees.CalculateExpectedSalary();varexperience=employees.GetExperience();vargithubLink=employees.GetGithubLink();vardata=new[]{expectedSalary,experience,githubLink};render(data);}}
Very good:
It is better to use a compact version of the code.
publicList<EmployeeData>ShowList(Employeeemployees){foreach(varemployeeinemployees){render(new[]{employee.CalculateExpectedSalary(),employee.GetExperience(),employee.GetGithubLink()});}}
Basic concept of testing
Testing is more important than shipping. If you have no tests or aninadequate amount, then every time you ship code you won't be sure that you didn't break anything. Deciding on what constitutes an adequate amount is up to your team, but having 100% coverage (all statements and branches) is how you achieve very high confidence and developer peace of mind. This means that in addition to having a great testing framework, you also need to use agood coverage tool.
There's no excuse to not write tests. There'splenty of good .NET test frameworks, so find one that your team prefers. When you find one that works for your team, then aim to always write tests for every new feature/module you introduce. If your preferred method is Test Driven Development (TDD), that is great, but the main point is to just make sure you are reaching your coverage goals before launching any feature, or refactoring an existing one.
Single concept per test
Ensures that your tests are laser focused and not testing miscellaenous (non-related) things, forcesAAA patern used to make your codes more clean and readable.
Bad:
publicclassMakeDotNetGreatAgainTests{[Fact]publicvoidHandleDateBoundaries(){vardate=newMyDateTime("1/1/2015");date.AddDays(30);Assert.Equal("1/31/2015",date);date=newMyDateTime("2/1/2016");date.AddDays(28);Assert.Equal("02/29/2016",date);date=newMyDateTime("2/1/2015");date.AddDays(28);Assert.Equal("03/01/2015",date);}}
Good:
publicclassMakeDotNetGreatAgainTests{[Fact]publicvoidHandle30DayMonths(){// Arrangevardate=newMyDateTime("1/1/2015");// Actdate.AddDays(30);// AssertAssert.Equal("1/31/2015",date);}[Fact]publicvoidHandleLeapYear(){// Arrangevardate=newMyDateTime("2/1/2016");// Actdate.AddDays(28);// AssertAssert.Equal("02/29/2016",date);}[Fact]publicvoidHandleNonLeapYear(){// Arrangevardate=newMyDateTime("2/1/2015");// Actdate.AddDays(28);// AssertAssert.Equal("03/01/2015",date);}}
Sourehttps://www.codingblocks.net/podcast/how-to-write-amazing-unit-tests
Use Async/Await
Summary of Asynchronous Programming Guidelines
| Name | Description | Exceptions |
|---|---|---|
| Avoid async void | Prefer async Task methods over async void methods | Event handlers |
| Async all the way | Don't mix blocking and async code | Console main method (C# <= 7.0) |
| Configure context | UseConfigureAwait(false) when you can | Methods that require context |
The Async Way of Doing Things
| To Do This ... | Instead of This ... | Use This |
|---|---|---|
| Retrieve the result of a background task | Task.Wait or Task.Result | await |
| Wait for any task to complete | Task.WaitAny | await Task.WhenAny |
| Retrieve the results of multiple tasks | Task.WaitAll | await Task.WhenAll |
| Wait a period of time | Thread.Sleep | await Task.Delay |
Best practice
The async/await is the best for IO bound tasks (networking communication, database communication, http request, etc.) but it is not good to apply on computational bound tasks (traverse on the huge list, render a hugge image, etc.). Because it will release the holding thread to the thread pool and CPU/cores available will not involve to process those tasks. Therefore, we should avoid using Async/Await for computional bound tasks.
For dealing with computational bound tasks, prefer to useTask.Factory.CreateNew withTaskCreationOptions isLongRunning. It will start a new background thread to process a heavy computational bound task without release it back to the thread pool until the task being completed.
Know Your Tools
There's a lot to learn about async and await, and it's natural to get a little disoriented. Here's a quick reference of solutions to common problems.
Solutions to Common Async Problems
| Problem | Solution |
|---|---|
| Create a task to execute code | Task.Run orTaskFactory.StartNew (not theTask constructor orTask.Start) |
| Create a task wrapper for an operation or event | TaskFactory.FromAsync orTaskCompletionSource<T> |
| Support cancellation | CancellationTokenSource andCancellationToken |
| Report progress | IProgress<T> andProgress<T> |
| Handle streams of data | TPL Dataflow or Reactive Extensions |
| Synchronize access to a shared resource | SemaphoreSlim |
| Asynchronously initialize a resource | AsyncLazy<T> |
| Async-ready producer/consumer structures | TPL Dataflow orAsyncCollection<T> |
Read theTask-based Asynchronous Pattern (TAP) document.It is extremely well-written, and includes guidance on API design and the proper use of async/await (including cancellation and progress reporting).
There are many new await-friendly techniques that should be used instead of the old blocking techniques. If you have any of these Old examples in your new async code, you're Doing It Wrong(TM):
| Old | New | Description |
|---|---|---|
task.Wait | await task | Wait/await for a task to complete |
task.Result | await task | Get the result of a completed task |
Task.WaitAny | await Task.WhenAny | Wait/await for one of a collection of tasks to complete |
Task.WaitAll | await Task.WhenAll | Wait/await for every one of a collection of tasks to complete |
Thread.Sleep | await Task.Delay | Wait/await for a period of time |
Task constructor | Task.Run orTaskFactory.StartNew | Create a code-based task |
Sourcehttps://gist.github.com/jonlabelle/841146854b23b305b50fa5542f84b20c
Basic concept of error handling
Thrown errors are a good thing! They mean the runtime has successfully identified when something in your program has gone wrong and it's letting you know by stopping function execution on the current stack, killing the process (in .NET/.NET Core), and notifying you in the console with a stack trace.
Don't use 'throw ex' in catch block
If you need to re-throw an exception after catching it, use just 'throw'By using this, you will save the stack trace. But in the bad option below,you will lost the stack trace.
Bad:
try{// Do something..}catch(Exceptionex){// Any action something like roll-back or logging etc.throwex;}
Good:
try{// Do something..}catch(Exceptionex){// Any action something like roll-back or logging etc.throw;}
Don't ignore caught errors
Doing nothing with a caught error doesn't give you the ability to ever fix or react to said error. Throwing the error isn't much better as often times it can get lost in a sea of things printed to the console. If you wrap any bit of code in atry/catch it means you think an error may occur there and therefore you should have a plan, or create a code path, for when it occurs.
Bad:
try{FunctionThatMightThrow();}catch(Exceptionex){// silent exception}
Good:
try{FunctionThatMightThrow();}catch(Exceptionerror){NotifyUserOfError(error);// Another optionReportErrorToService(error);}
Use multiple catch block instead of if conditions.
If you need to take action according to type of the exception,you better use multiple catch block for exception handling.
Bad:
try{// Do something..}catch(Exceptionex){if(exisTaskCanceledException){// Take action for TaskCanceledException}elseif(exisTaskSchedulerException){// Take action for TaskSchedulerException}}
Good:
try{// Do something..}catch(TaskCanceledExceptionex){// Take action for TaskCanceledException}catch(TaskSchedulerExceptionex){// Take action for TaskSchedulerException}
Keep exception stack trace when rethrowing exceptions
C# allows the exception to be rethrown in a catch block using thethrow keyword. It is a bad practice to throw a caught exception usingthrow e;. This statement resets the stack trace. Instead usethrow;. This will keep the stack trace and provide a deeper insight about the exception.Another option is to use a custom exception. Simply instantiate a new exception and set its inner exception property to the caught exception with thrownew CustomException("some info", e);. Adding information to an exception is a good practice as it will help with debugging. However, if the objective is to log an exception then usethrow; to pass the buck to the caller.
Bad:
try{FunctionThatMightThrow();}catch(Exceptionex){logger.LogInfo(ex);throwex;}
Good:
try{FunctionThatMightThrow();}catch(Exceptionerror){logger.LogInfo(error);throw;}
Good:
try{FunctionThatMightThrow();}catch(Exceptionerror){logger.LogInfo(error);thrownewCustomException(error);}
Uses.editorconfig file
Bad:
Has many code formatting styles in the project. For example, indent style isspace andtab mixed in the project.
Good:
Define and maintain consistent code style in your codebase with the use of an.editorconfig file
root=true[*]indent_style=spaceindent_size=2end_of_line= lfcharset= utf-8trim_trailing_whitespace= trueinsert_final_newline= true# C# files[*.cs]indent_size=4# New line preferencescsharp_new_line_before_open_brace= allcsharp_new_line_before_else= truecsharp_new_line_before_catch= truecsharp_new_line_before_finally= truecsharp_new_line_before_members_in_object_initializers= truecsharp_new_line_before_members_in_anonymous_types= truecsharp_new_line_within_query_expression_clauses= true#Code files[*.{cs,csx,vb,vbx}]indent_size=4#Indentation preferencescsharp_indent_block_contents= truecsharp_indent_braces= falsecsharp_indent_case_contents= truecsharp_indent_switch_labels= truecsharp_indent_labels=one_less_than_current# avoidthis. unless absolutely necessarydotnet_style_qualification_for_field= false:suggestiondotnet_style_qualification_for_property= false:suggestiondotnet_style_qualification_for_method= false:suggestiondotnet_style_qualification_for_event= false:suggestion# only use varwhen it's obvious what the variable typeis# csharp_style_var_for_built_in_types= false:none# csharp_style_var_when_type_is_apparent= false:none# csharp_style_var_elsewhere= false:suggestion# use language keywords instead of BCL typesdotnet_style_predefined_type_for_locals_parameters_members= true:suggestiondotnet_style_predefined_type_for_member_access= true:suggestion# name all constant fieldsusingPascalCasedotnet_naming_rule.constant_fields_should_be_pascal_case.severity=suggestiondotnet_naming_rule.constant_fields_should_be_pascal_case.symbols=constant_fieldsdotnet_naming_rule.constant_fields_should_be_pascal_case.style=pascal_case_styledotnet_naming_symbols.constant_fields.applicable_kinds=fielddotnet_naming_symbols.constant_fields.required_modifiers=constdotnet_naming_style.pascal_case_style.capitalization= pascal_case#staticfields should have s_ prefixdotnet_naming_rule.static_fields_should_have_prefix.severity=suggestiondotnet_naming_rule.static_fields_should_have_prefix.symbols=static_fieldsdotnet_naming_rule.static_fields_should_have_prefix.style=static_prefix_styledotnet_naming_symbols.static_fields.applicable_kinds=fielddotnet_naming_symbols.static_fields.required_modifiers=staticdotnet_naming_style.static_prefix_style.required_prefix=s_dotnet_naming_style.static_prefix_style.capitalization=camel_case# internal and privatefields shouldbe _camelCasedotnet_naming_rule.camel_case_for_private_internal_fields.severity=suggestiondotnet_naming_rule.camel_case_for_private_internal_fields.symbols=private_internal_fieldsdotnet_naming_rule.camel_case_for_private_internal_fields.style=camel_case_underscore_styledotnet_naming_symbols.private_internal_fields.applicable_kinds=fielddotnet_naming_symbols.private_internal_fields.applicable_accessibilities=private,internaldotnet_naming_style.camel_case_underscore_style.required_prefix=_dotnet_naming_style.camel_case_underscore_style.capitalization=camel_case#Code styledefaultsdotnet_sort_system_directives_first= truecsharp_preserve_single_line_blocks= truecsharp_preserve_single_line_statements= false#Expression-level preferencesdotnet_style_object_initializer= true:suggestiondotnet_style_collection_initializer= true:suggestiondotnet_style_explicit_tuple_names= true:suggestiondotnet_style_coalesce_expression= true:suggestiondotnet_style_null_propagation= true:suggestion# Expression-bodied memberscsharp_style_expression_bodied_methods= false:nonecsharp_style_expression_bodied_constructors= false:nonecsharp_style_expression_bodied_operators= false:nonecsharp_style_expression_bodied_properties= true:nonecsharp_style_expression_bodied_indexers= true:nonecsharp_style_expression_bodied_accessors= true:none# Pattern matchingcsharp_style_pattern_matching_over_is_with_cast_check= true:suggestioncsharp_style_pattern_matching_over_as_with_null_check= true:suggestioncsharp_style_inlined_variable_declaration= true:suggestion# Null checking preferencescsharp_style_throw_expression= true:suggestioncsharp_style_conditional_delegate_call= true:suggestion# Space preferencescsharp_space_after_cast= falsecsharp_space_after_colon_in_inheritance_clause= truecsharp_space_after_comma= truecsharp_space_after_dot= falsecsharp_space_after_keywords_in_control_flow_statements= truecsharp_space_after_semicolon_in_for_statement= truecsharp_space_around_binary_operators= before_and_aftercsharp_space_around_declaration_statements= do_not_ignorecsharp_space_before_colon_in_inheritance_clause= truecsharp_space_before_comma= falsecsharp_space_before_dot= falsecsharp_space_before_open_square_brackets= falsecsharp_space_before_semicolon_in_for_statement= falsecsharp_space_between_empty_square_brackets= falsecsharp_space_between_method_call_empty_parameter_list_parentheses= falsecsharp_space_between_method_call_name_and_opening_parenthesis= falsecsharp_space_between_method_call_parameter_list_parentheses= falsecsharp_space_between_method_declaration_empty_parameter_list_parentheses= falsecsharp_space_between_method_declaration_name_and_open_parenthesis= falsecsharp_space_between_method_declaration_parameter_list_parentheses= falsecsharp_space_between_parentheses= falsecsharp_space_between_square_brackets= false[*.{asm,inc}]indent_size=8#Xml projectfiles[*.{csproj,vcxproj,vcxproj.filters,proj,nativeproj,locproj}]indent_size=2#Xml configfiles[*.{props,targets,config,nuspec}]indent_size=2[CMakeLists.txt]indent_size=2[*.cmd]indent_size=2
Avoid positional markers
They usually just add noise. Let the functions and variable names along with the proper indentation and formatting give the visual structure to your code.
Bad:
////////////////////////////////////////////////////////////////////////////////// Scope Model Instantiation////////////////////////////////////////////////////////////////////////////////varmodel=new[]{menu:'foo',nav:'bar'};////////////////////////////////////////////////////////////////////////////////// Action setup////////////////////////////////////////////////////////////////////////////////voidActions(){// ...};
Bad:
#region Scope Model Instantiationvarmodel={menu:'foo',nav:'bar'};#endregion#region Action setupvoidActions(){// ...};#endregion
Good:
varmodel=new[]{menu:'foo',nav:'bar'};voidActions(){// ...};
Don't leave commented out code in your codebase
Version control exists for a reason. Leave old code in your history.
Bad:
doStuff();// doOtherStuff();// doSomeMoreStuff();// doSoMuchStuff();
Good:
doStuff();
Don't have journal comments
Remember, use version control! There's no need for dead code, commented code, and especially journal comments. Usegit log to get history!
Bad:
/** * 2018-12-20: Removed monads, didn't understand them (RM) * 2017-10-01: Improved using special monads (JP) * 2016-02-03: Removed type-checking (LI) * 2015-03-14: Added combine with type-checking (JR) */publicintCombine(inta,intb){returna+b;}
Good:
publicintCombine(inta,intb){returna+b;}
Only comment things that have business logic complexity
Comments are an apology, not a requirement. Good codemostly documents itself.
Bad:
publicintHashIt(stringdata){// The hashvarhash=0;// Length of stringvarlength=data.length;// Loop through every character in datafor(vari=0;i<length;i++){// Get character code.constchar=data.charCodeAt(i);// Make the hashhash=((hash<<5)-hash)+char;// Convert to 32-bit integerhash&=hash;}}
Better but still Bad:
publicintHashIt(stringdata){varhash=0;varlength=data.length;for(vari=0;i<length;i++){constchar=data.charCodeAt(i);hash=((hash<<5)-hash)+char;// Convert to 32-bit integerhash&=hash;}}
If a comment explains WHAT the code is doing, it is probably a useless comment and can be implemented with a well named variable or function. The comment in the previous code could be replaced with a function namedConvertTo32bitInt so this comment is still useless.However it would be hard to express by code WHY the developer chose djb2 hash algorithm instead of sha-1 or another hash function. In that case a comment is acceptable.
Good:
publicintHash(stringdata){varhash=0;varlength=data.length;for(vari=0;i<length;i++){varcharacter=data[i];// use of djb2 hash algorithm as it has a good compromise// between speed and low collision with a very simple implementationhash=((hash<<5)-hash)+character;hash=ConvertTo32BitInt(hash);}returnhash;}privateintConvertTo32BitInt(intvalue){returnvalue&value;}
- clean-code-javascript - Clean Code concepts adapted for JavaScript
- clean-code-php - Clean Code concepts adapted for PHP
- clean-code-ruby - Clean Code concepts adapted for Ruby
- clean-code-python - Clean Code concepts adapted for Python
- clean-code-typescript - Clean Code concepts adapted for TypeScript
- clean-go-article - Clean Code concepts adapted for Golang and an example how to applyclean code in Golang
- clean-abap - Clean Code concepts adapted for ABAP
- programming-principles - Categorized overview of Programming Principles & Patterns
- Elixir-Code-Smells - Catalog of Elixir-specific code smells
- awesome-clean-code - Design principles, featured articles, tutorials, videos, code examples, blogs and books
- Google Styleguides - This project holds the C++ Style Guide, Swift Style Guide, Objective-C Style Guide, Java Style Guide, Python Style Guide, R Style Guide, Shell Style Guide, HTML/CSS Style Guide, JavaScript Style Guide, AngularJS Style Guide, Common Lisp Style Guide, and Vimscript Style Guide
- Django Styleguide - Django styleguide used in HackSoft projects
- nodebestpractices - The Node.js best practices list
- codemaid - open source Visual Studio extension to cleanup and simplify our C#, C++, F#, VB, PHP, PowerShell, JSON, XAML, XML, ASP, HTML, CSS, LESS, SCSS, JavaScript and TypeScript coding
- Sharpen - Visual Studio extension that intelligently introduces new C# features into your existing code base
- tslint-clean-code - TSLint rules for enforcing Clean Code
- AspNetCoreDiagnosticScenarios - Examples of broken patterns in ASP.NET Core applications
- Clean Code - The summary ofClean Code: A Handbook of Agile Software Craftsmanship book
- Clean Architecture - The summary ofClean Architecture: A Craftsman's Guide to Software Structure and Design book
- Modern JavaScript Cheatsheet - Cheatsheet for the JavaScript knowledge you will frequently encounter in modern projects
- OWASP Cheat Sheet Series - Cheatsheet was created to provide a concise collection of high value information on specific application security topics
- .NET Memory Performance Analysis - This document aims to help folks who develop applications in .NET with how to think about memory performance analysis and finding the right approaches to perform such analysis if they need to. In this context .NET includes .NET Framework and .NET Core. In order to get the latest memory improvements in both the garbage collector and the rest of the framework I strongly encourage you to be on .NET Core if you are not already, because that’s where the active development happens
- naming-cheatsheet - Comprehensive language-agnostic guidelines on variables naming
- 101 Design Patterns & Tips for Developers
- Go Concurrency Guide
- Cognitive Load In Software Development
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