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Coding Guidelines

The most important rule when contributing to a source code base – any source code, not just an open source project – is to keep the style consistent. To enable that consistency, our command line build runs both FxCop and StyleCop to attempt to catch both common programmer errors as well as to enforce a common style. Please observe the general rule to leave all the code looking consistent: that includes new files being consistent with the existing style. Any pull requests which include major reformatting of the source code or deviate dramatically from the normal style will be declined and asked to resubmit once they’re amended.


  • Camel case is a casing convention where the first letter is lower-case, words are not separated by any character but subsequent words have their first letters capitalized. Example: thisIsCamelCased.
  • Pascal case is a casing convention where the first letter of each word is capitalized, and no separating character is included between words. Example: ThisIsPascalCased.

C# coding conventions

In general, we have striven to use a style which is compatible with the out-of-the-box defaults for Visual Studio. In particular, this means we use Allman bracing style.

Some other rules we follow:

  • Private fields are prefixed with an underscore and camel-cased.
  • Always include curly braces around blocks, even when they would be optional.
  • Using statements go at the top of the file, before the namespace declaration, with System directives first.
    (For Visual Studio 2012, turn on the setting at Tools, Options, Text Editor, C#, Advanced, Organize Usings, Place 'System' directives first when sorting usings.)
  • Use of regions (#region) is not permitted.
  • Using var is okay, if and only if the type is obvious (namely, for “new” statements, cast statements, or anonymous object).
  • All production code must have associated unit tests.
  • All new production code should have at least rudimentary XML doc comments.
  • Prefer postfix operations (x++) to prefix operations (++x) when there is no difference in behavior.

Examples of var usage

// This is ok
var tuple = new { Name = >"John", Age = 50 }; 

// This is ok
var stream = new MemoryStream();

// This is ok
var product = (Product)GetProduct();

// This is NOT ok
var values = GetProducts();

Example of the source code style

using System;

namespace System.Web.Http
    public class ClassName
        private List<SomeType> _privateMember;

        public List<SomeType> ShortProperty
            get { return _privateMember; }

        public string AutoProperty { get; set; }

        public int ComplexProperty
                if (someCondition)
                    return 42;
                    return 2112;

        public string SomeMethod(Status status)
            switch (status)
                case Status.Foo:
                    return "It was a Foo";

                case Status.Bar:
                    return "Turns out it was a Bar";

                    return "I’m honestly not sure what it was";

JavaScript coding conventions

  • Namespaces are Pascal-cased.
  • Class names are Pascal-cased.
  • Properties, fields and local variables are camel-cased.
  • Parameters are camel-cased.
  • Functions which are class constructors are Pascal-cased; all other functions are camel-cased.
  • Use the K&R style for opening braces (put the opening brace on the opening line). This is because in JavaScript, the semicolon is optional, which can cause difficult to spot bugs (see for an example).
  • In general, if your code makes JSLint happy, it’ll make us happy, too.

Last edited Oct 24, 2012 at 12:06 AM by davidmatson, version 6


amirkarimi Mar 29, 2012 at 10:17 PM 
Why don't you use the StyleCop rules about private fields (Prefixing with underscore) and using "this" keyword instead of prefixes. Would you please explain your reasons about these rules?