Coding conventions

Use of C# and .NET features

Noda Time targets .NET 3.5, and the code only uses features available in C# 3. While we normally build against a C# 4 or C# 5 compiler, most later features aren't useful:

  • Dynamic typing requires .NET 4
  • Generic variance relies on the appropriate attributes being applied to the types in question, and the most useful types (e.g. IEnumerable<T>) don't have those attributes in .NET 3.5
  • Async methods require .NET 4.5, or .NET 4 with the async targeting pack
  • The iteration variable capture rules for foreach would require all developers to use C# 5 compilers. Please do not rely on this.
  • Optional parameters wouldn't be useful to C# 3 users, so our API design assumes they're not available
  • Caller member info attributes require .NET 4.5.

Additionally, we're trying not to use framework features we don't need to gratuitously, in case we ever want to backport to .NET 2.0. That's unlikely given that it would mean dropping TimeZoneInfo support, but it's always a possibility. Additionally, we're very likely to want to create a Portable Class Library at some point, so where possible, stick to core features which won't make this harder than it needs to be. (Don't worry too much though - don't feel you need to look up every member.)

PCL support

See the Installation section of the user guide for which versions of the PCL are currently supported. Supporting Silverlight restricts us more than the other targets; in particular the System.IO.Compression namespace is entirely absent from Silverlight, whereas it's present in the other PCL targets we're supporting.

The PCL build is a separate project configuration, hand-crafted into the existing project files. These configurations define the PCL conditional compilation symbol, which is used for areas where the code needs to differ between builds.

Code Layout

  • Use the Visual Studio default settings in Tools | Options | Text Editor | C# | Formatting.
  • Use spaces not tabs (discussion).

File Layout

  • Place using statements at the top of the file (not in the namespace).
  • A single namespace in any one file.
  • Prefer a single type in a file.


using System;

namespace ConsoleApplication1
    class Program
        static void Main(string[] args)
            if (args.Length > 1)
                Console.WriteLine("Hello " + args[0]);
                Console.WriteLine("Hello world!");

Working With Multiple C# Formatting Configurations

Using Tools | Import and Export Settings the C# formatting settings can be selectively saved and then reloading. All the C# formatting options fall under All Options | Options | Text Editor | C# Editor. (The "C#" option holds the non-formatting settings.)

Naming of tests

Follow a Method_State_Result pattern:

  • Method is the name of the method being tested, possibly with some more information for overload disambiguation
  • State describes the scenario that is being tested
  • Result describes what is the expected behavior

When any of the last two is really redundant, it can be omitted, like when the State would be ValidValues or similar, or the Result would be ItWorks.