Dot Net Coding Standards Part2

01:32
8.    Indentation and Spacing

1.     Use TAB for indentation. Do not use SPACES.  Define the Tab size as 4.
2.     Comments should be in the same level as the code (use the same level of indentation).
Good:

// Format a message and display

string fullMessage = "Hello " + name;
DateTime currentTime = DateTime.Now;
string message = fullMessage + ", the time is : " + currentTime.ToShortTimeString();
MessageBox.Show ( message );

Not Good:

// Format a message and display
string fullMessage = "Hello " + name;
DateTime currentTime = DateTime.Now;
string message = fullMessage + ", the time is : " + currentTime.ToShortTimeString();
MessageBox.Show ( message );

3.Curly braces ( {} ) should be in the same level as the code outside the braces
4.     Use one blank line to separate logical groups of code.

Good:
       bool SayHello ( string name )
       {
              string fullMessage = "Hello " + name;
              DateTime currentTime = DateTime.Now;

              string message = fullMessage + ", the time is : " + currentTime.ToShortTimeString();

              MessageBox.Show ( message );

              if ( ... )
              {
                     // Do something
                     // ...

                     return false;
              }

              return true;
       }

Not Good:

       bool SayHello (string name)
       {
              string fullMessage = "Hello " + name;
              DateTime currentTime = DateTime.Now;
              string message = fullMessage + ", the time is : " + currentTime.ToShortTimeString();
              MessageBox.Show ( message );
              if ( ... )
              {
                     // Do something
                     // ...
                     return false;
              }
              return true;
       }
5.     There should be one and only one single blank line between each method inside the class.
6.     The curly braces should be on a separate line and not in the same line as if, for etc.

Good:
              if ( ... )   
              {
                     // Do something
              }

Not Good:

              if ( ... )    {
                     // Do something
              }

7.     Use a single space before and after each operator and brackets.

Good:
              if ( showResult == true )
              {
                     for ( int i = 0; i < 10; i++ )
                     {
                           //
                     }
              }

Not Good:

              if(showResult==true)
              {
                     for(int          i= 0;i<10;i++)
                     {
                           //
                     }
              }
8.     Use #region to group related pieces of code together. If you use proper grouping using #region, the page should like this when all definitions are collapsed.
9.     Keep private member variables, properties and methods in the top of the file and public members in the bottom. 

9.    Good Programming practices

1.     Avoid writing very long methods. A method should typically have 1~25 lines of code. If a method has more than 25 lines of code, you must consider re factoring into separate methods.
2.     Method name should tell what it does. Do not use mis-leading names. If the method name is obvious, there is no need of documentation explaining what the method does.

Good:
       void SavePhoneNumber ( string phoneNumber )
       {
              // Save the phone number.
       }

Not Good:

       // This method will save the phone number.
       void SaveDetails ( string phoneNumber )
       {
              // Save the phone number.
       }

3.     A method should do only 'one job'. Do not combine more than one job in a single method, even if those jobs are very small.

Good:
       // Save the address.
       SaveAddress (  address );
      
       // Send an email to the supervisor to inform that the address is updated.
       SendEmail ( address, email );           
      
       void SaveAddress ( string address )
       {
              // Save the address.
              // ...
       }
      
       void SendEmail ( string address, string email )
       {
              // Send an email to inform the supervisor that the address is changed.
              // ...
       }

Not Good:

       // Save address and send an email to the supervisor to inform that
// the address is updated.
       SaveAddress ( address, email );

       void SaveAddress ( string address, string email )
       {
              // Job 1.
              // Save the address.
              // ...

              // Job 2.
              // Send an email to inform the supervisor that the address is changed.
              // ...
       }

4.     Use the c# or VB.NET specific types (aliases), rather than the types defined in System namespace.

       int age;   (not Int16)
       string name;  (not String)
       object contactInfo; (not Object)

               
Some developers prefer to use types in Common Type System than language specific aliases.

5.     Always watch for unexpected values. For example, if you are using a parameter with 2 possible values, never assume that if one is not matching then the only possibility is the other value.

Good:

If ( memberType == eMemberTypes.Registered )
{
       // Registered user… do something…
}
else if ( memberType == eMemberTypes.Guest )
{
       // Guest user... do something…
}
else
{
              // Un expected user type. Throw an exception
              throw new Exception (“Un expected value “ + memberType.ToString() + “’.”)

              // If we introduce a new user type in future, we can easily find
// the problem here.
}

Not Good:

If ( memberType == eMemberTypes.Registered )
{
              // Registered user… do something…
}
else
{
              // Guest user... do something…

// If we introduce another user type in future, this code will
// fail and will not be noticed.
}
1.     Do not hardcode numbers. Use constants instead. Declare constant in the top of the file and use it in your code.

However, using constants are also not recommended. You should use the constants in the config file or database so that you can change it later. Declare them as constants only if you are sure this value will never need to be changed.

2.     Do not hardcode strings. Use resource files.

3.     Convert strings to lowercase or upper case before comparing. This will ensure the string will match even if the string being compared has a different case.

if ( name.ToLower() == “john” )
{
           //…
}

4.     Use String.Empty instead of “”

Good:

If ( name == String.Empty )
{
       // do something
}

Not Good:

If ( name == “” )
{
       // do something
}


5.     Avoid using member variables. Declare local variables wherever necessary and pass it to other methods instead of sharing a member variable between methods. If you share a member variable between methods, it will be difficult to track which method changed the value and when.

6.     Use enum wherever required. Do not use numbers or strings to indicate discrete values.

Good:
       enum MailType
       {
              Html,
              PlainText,
              Attachment
       }

       void SendMail (string message, MailType mailType)
       {
              switch ( mailType )
              {
                     case MailType.Html:
                           // Do something
                           break;
                     case MailType.PlainText:
                           // Do something
                           break;
                     case MailType.Attachment:
                           // Do something
                           break;
                     default:
                           // Do something
                           break;
              }
       }


Not Good:

       void SendMail (string message, string mailType)
       {
              switch ( mailType )
              {
                     case "Html":
                           // Do something
                           break;
                     case "PlainText":
                           // Do something
                           break;
                     case "Attachment":
                           // Do something
                           break;
                     default:
                           // Do something
                           break;
              }
       }
7.     Do not make the member variables public or protected. Keep them private and expose public/protected Properties.

8.     The event handler should not contain the code to perform the required action. Rather call another method from the event handler.

9.     Do not programmatically click a button to execute the same action you have written in the button click event. Rather, call the same method which is called by the button click event handler.

10.  Never hardcode a path or drive name in code. Get the application path programmatically and use relative path.

11.  Never assume that your code will run from drive "C:". You may never know, some users may run it from network or from a "Z:".

12.  In the application start up, do some kind of "self check" and ensure all required files and dependancies are available in the expected locations. Check for database connection in start up, if required. Give a friendly message to the user in case of any problems.

13.  If the required configuration file is not found, application should be able to create one with default values.

14.  If a wrong value found in the configuration file, application should throw an error or give a message and also should tell the user what are the correct values.

15.  Error messages should help the user to solve the problem. Never give error messages like "Error in Application", "There is an error" etc. Instead give specific messages like "Failed to update database. Please make sure the login id and password are correct."

16.  When displaying error messages, in addition to telling what is wrong, the message should also tell what should the user do to solve the problem. Instead of message like "Failed to update database.", suggest what should the user do: "Failed to update database. Please make sure the login id and password are correct."

17.  Show short and friendly message to the user. But log the actual error with all possible information. This will help a lot in diagnosing problems.

18.  Do not have more than one class in a single file.

19.  Have your own templates for each of the file types in Visual Studio. You can include your company name, copy right information etc in the template. You can view or edit the Visual Studio file templates in the folder C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\ItemTemplatesCache\CSharp\1033. (This folder has the templates for C#, but you can easily find the corresponding folders or any other language)

20.  Avoid having very large files. If a single file has more than 1000 lines of code, it is a good candidate for refactoring. Split them logically into two or more classes.

21.   Avoid public methods and properties, unless they really need to be accessed from outside the class. Use “internal” if they are accessed only within the same assembly.

22.   Avoid passing too many parameters to a method. If you have more than 4~5 parameters, it is a good candidate to define a class or structure.

23.   If you have a method returning a collection, return an empty collection instead of null, if you have no data to return. For example, if you have a method returning an ArrayList, always return a valid ArrayList. If you have no items to return, then return a valid ArrayList with 0 items. This will make it easy for the calling application to just check for the “count” rather than doing an additional check for “null”.

24.   Use the AssemblyInfo file to fill information like version number, description, company name, copyright notice etc.

25.   Logically organize all your files within appropriate folders. Use 2 level folder hierarchies. You can have up to 10 folders in the root folder and each folder can have up to 5 sub folders. If you have too many folders than cannot be accommodated with the above mentioned 2 level hierarchy, you may need re factoring into multiple assemblies.

Make sure you have a good logging class which can be configured to log errors, warning or traces. If you configure to log errors, it should only log errors. But if you configure to log traces, it should record all (errors, warnings and trace). Your log class should be written such
1.     a way that in future you can change it easily to log to Windows Event Log, SQL Server, or Email to administrator or to a File etc without any change in any other part of the application. Use the log class extensively throughout the code to record errors, warning and even trace messages that can help you trouble shoot a problem.

2.     If you are opening database connections, sockets, file stream etc, always close them in the finally block. This will ensure that even if an exception occurs after opening the connection, it will be safely closed in the finally block.

3.     Declare variables as close as possible to where it is first used. Use one variable declaration per line.

4.     Use StringBuilder class instead of String when you have to manipulate string objects in a loop. The String object works in weird way in .NET. Each time you append a string, it is actually discarding the old string object and recreating a new object, which is a relatively expensive operations.

Consider the following example:

public string ComposeMessage (string[] lines)
{
   string message = String.Empty;

   for (int i = 0; i < lines.Length; i++)
   {
      message += lines [i];
   }

   return message;
}

In the above example, it may look like we are just appending to the string object ‘message’. But what is happening in reality is, the string object is discarded in each iteration and recreated and appending the line to it.

If your loop has several iterations, then it is a good idea to use StringBuilder class instead of String object.

See the example where the String object is replaced with StringBuilder.

public string ComposeMessage (string[] lines)
{
    StringBuilder message = new StringBuilder();

    for (int i = 0; i < lines.Length; i++)
    {
       message.Append( lines[i] );
    }

    return message.ToString();
}