Internal Coding Guidelines

An abridged version of Brad Abrams coding guidelines courtesy of Nigel Belham with minor layout modifications for increased clarity.

Introduction

First, read the .NET Framework Design Guidelines. Almost all naming conventions, casing rules, etc., are spelled out in this document. Unlike the Design Guidelines document, you should treat this document as a set of suggested guidelines. These generally do not affect the customer view so they are not required.

Style Guidelines

Tabs & Indenting

Tab characters (\0×09) should not be used in C# code files. All indentation should be done with 4 space characters.

Bracing

Open braces should always be at the beginning of the line after the statement that begins the block. Contents of the brace should be indented by 4 spaces. For example:

if (someExpression)
{
   DoSomething();
}
else
{
   DoSomethingElse();
}

“case” statements should be indented from the switch statement like this:

switch (someExpression)
{
 
   case 0:
      DoSomething();
      break;
 
   case 1:
      DoSomethingElse();
      break;
 
   case 2:
      {
         int n = 1;
         DoAnotherThing(n);
      }
      break;
}

Braces should never be considered optional. Even for single statement blocks, you should always use braces. This increases code readability and maintainability.

for (int i=0; i<100; i++) { DoSomething(i); }

Single line statements

Single line statements can have braces that begin and end on the same line.

public class Foo
{
   int bar;
 
   public int Bar
   {
      get { return bar; }
      set { bar = value; }
   }
 
}

It is suggested that all control structures (if, while, for, etc.) use braces, but it is not required.

Commenting

Comments should be used to describe intention, algorithmic overview, and/or logical flow. It would be ideal, if from reading the comments alone, someone other than the author could understand a function’s intended behaviour and general operation. While there are no minimum comment requirements and certainly some very small routines need no commenting at all, it is hoped that most routines will have comments reflecting the programmer’s intent and approach.

Copyright notice

Each file should start with a copyright notice. To avoid errors in doc comment builds, you don’t want to use triple-slash doc comments, but using XML makes the comments easy to replace in the future. Final text will vary by product (you should contact legal for the exact text), but should be similar to:

//---------------------------------------------------------------
//
//     Copyright (c) Microsoft Corporation.  All rights reserved.
//
//---------------------------------------------------------------

Documentation Comments

All methods should use XML doc comments. For internal dev comments, the <devdoc> tag should be used.

public class Foo
{
 
/// Public stuff about the method
///
What a neat parameter!
/// Cool internal stuff!
///
public void MyMethod(int bar) { … }
 
}

However, it is common that you would want to move the XML documentation to an external file – for that, use the <include> tag.

public class Foo
{
 
   ///
   ///
   public void MyMethod(int bar) { … }
 
}

Comment Style

The // (two slashes) style of comment tags should be used in most situations. Where ever possible, place comments above the code instead of beside it. Here are some examples:

public class SomethingUseful
{
    private int          itemHash;            // instance member
    private static bool  hasDoneSomething;    // static member
}

Spacing

Spaces improve readability by decreasing code density. Here are some guidelines for the use of space characters within code:

• Do use a single space after a comma between function arguments.
  Right: Console.In.Read(myChar, 0, 1);
  Wrong: Console.In.Read(myChar,0,1);
• Do not use a space after the parenthesis and function arguments
  Right: CreateFoo(myChar, 0, 1)
  Wrong: CreateFoo( myChar, 0, 1 )
• Do not use spaces between a function name and parenthesis.
  Right: CreateFoo()
  Wrong: CreateFoo ()
• Do not use spaces inside brackets.
  Right: x = dataArray[index];
  Wrong: x = dataArray[ index ];
• Do use a single space before flow control statements
  Right: while (x == y)
  Wrong: while(x==y)
• Do use a single space before and after comparison operators
  Right: if (x == y)
  Wrong: if (x==y)

Naming

Follow all .NET Framework Design Guidelines for both internal and external members. Highlights of these include:

• Do not use Hungarian notation
• Do not use a prefix for member variables (_, m_, s_, etc.). If you want to distinguish between local and member variables you should use “this.” in C# and “Me.” in VB.NET.
• Do use camelCasing for member variables
• Do use camelCasing for parameters
• Do use camelCasing for local variables
• Do use PascalCasing for function, property, event, and class names
• Do prefix interfaces names with “I”
• Do not prefix enums, classes, or delegates with any letter

The reasons to extend the public rules (no Hungarian, no prefix for member variables, etc.) is to produce a consistent source code appearance. In addition a goal is to have clean readable source. Code legibility should be a primary goal.

Naming Conventions

Interop Classes

Classes that are there for interop wrappers (DllImport statements) should follow the naming convention below:

• NativeMethods – No suppress unmanaged code attribute, these are methods that can be used anywhere because a stack walk will be performed.
• UnsafeNativeMethods – Has suppress unmanaged code attribute. These methods are potentially dangerous and any caller of these methods must do a full security review to ensure that the usage is safe and protected as no stack walk will be performed.
• SafeNativeMethods – Has suppress unmanaged code attribute. These methods are safe and can be used fairly safely and the caller isn’t needed to do full security reviews even though no stack walk will be performed.

class NativeMethods
{
   private NativeMethods() {}
 
   [DllImport(“user32”)]
   internal static extern void FormatHardDrive(string driveName);
}
 
[SuppressUnmanagedCode]
class UnsafeNativeMethods
{
   private UnsafeNativeMethods() {}
 
   [DllImport(“user32”)]
   internal static extern void CreateFile(string fileName);
}
 
[SuppressUnmanagedCode]
class SafeNativeMethods
{
   private SafeNativeMethods() {}
 
   [DllImport(“user32”)]
   internal static extern void MessageBox(string text);
}

All interop classes must be private, and all methods must be internal. In addition a private constructor should be provided to prevent instantiation.

File Organization

• Source files should contain only one public type, although multiple internal classes are allowed
• Source files should be given the name of the public class in the file
• Directory names should follow the namespace for the class

For example, I would expect to find the public class “System.Windows.Forms.Control” in “System\Windows\Forms\Control.cs”…

• Classes member should be alphabetized, and grouped into sections (Fields, Constructors, Properties, Events, Methods, Private interface implementations, Nested types)
• Using statements should be inside the namespace declaration.

namespace MyNamespace
{
 
using System;
 
public class MyClass : IFoo
{
 
      // fields
      int foo;
 
      // constructors
      public MyClass() { … }
 
      // properties
      public int Foo { get { … } set { … } }
 
      // events
      public event EventHandler FooChanged { add { … } remove { … } }
 
      // methods
      void DoSomething() { … }
      void FindSomethind() { … }
 
//private interface implementations
   void IFoo.DoSomething() { DoSomething(); }
 
// nested types
   class NestedType { … }
 
}
 
}