#531 – Best Practices for Naming Namespaces

In C#, a namespace declaration specifies the name of the namespace and you can use any valid C# identifier as the name.  However, it’s generally considered good practice to follow the suggestions listed below when naming namespaces.

• Use Pascal Casing for each portion of the namespace, capitalizing the first letter of each word.  E.g. Acme.AfricanAnimalLibrary
• Do not use underscores
• Use sub-namespaces to organize/group related namespaces
• The highest two levels of namespaces should follow the pattern CompanyName.ProductName or CompanyName.TechnologyName.  E.g. Acme.SearchEngine.Logging or Acme.Rendering.3DTools

Incorporating your company or organization name into the namespace hierarchy helps ensure that your types are globally unique.

#527 – Defining a Nested Namespace Using Dot Notation

If you are defining a type that exists in a nested namespace, there are two ways to define the namespace.  You can nest the namespace keywords or you can use a dot notation to define the full namespace path.

Let’s say that we’re defining the new type DogLogger and placing it in the DogLibrary.Utility namespace.  You can nest the namespace keywords as shown below.

namespace DogLibrary
{
    namespace Utility
    {
        public class DogLogger
        {
        }
    }
}

You can also just include a single namespace keyword, fully specifying the DogLibrary.Utility namespace.

namespace DogLibrary.Utility
{
    public class DogLogger
    {
    }
}

#524 – All Types Within a Namespace Must Be Unique

You can create more than one type with the same name, as long as the exist in different namespaces.  But within a particular namespace, the name of every type must be unique.

In the example below, we declare a Dog class in both the EarthDogs and AlienDogs namespaces.

namespace EarthDogs
{
    public class Dog
    {
        public string Name { get; set; }

        public void Bark()
        {
            Console.WriteLine("Woooof");
        }
    }
}

namespace AlienDogs
{
    public class Dog
    {
        public string Name { get; set; }

        public void Bark()
        {
            Console.WriteLine("Snarkzuggrootzen");
        }
    }
}

(In practice, for these classes, you’d probably instead declare a Dog parent class and subclasses EarthDog and AlienDog, which would override the Bark method).

#522 – The Fully Qualified Name for a Type Includes the Namespace

If we define a Dog type in the DogLibrary namespace, the fully qualified name for the new type is DogLibrary.Dog.  You can use this full name when working with the type.

            DogLibrary.Dog kirby = new DogLibrary.Dog();
            kirby.Bark();

If you’re writing code that exists in the same namespace as a type, you can omit the namespace and just use the short version of the type name.

namespace DogLibrary
{
    public class Dog
    {
        public string Name { get; set; }
        public int Age { get; set; }

        public void Bark()
        {
            Console.WriteLine("WOOOOOF!");
        }
    }

    public static class DogFactory
    {
        public static Dog MakeDog(string name, int age)
        {
            // Can just use "Dog" as type name
            Dog d = new Dog();
            d.Name = name;
            d.Age = age;
            return d;
        }
    }
}