#727 – Get a List of All Namespaces in an Assembly

While you can’t explicitly get a list of all namespaces within a .NET assembly, you can iterate through all types in the assembly and build up a list of namespaces.

Below is some sample code that organizes all types in an assembly, by namespace.

        static void Main()
        {
            // Build list of all types :
            //   SortedList<namespace-name, SortedList<type-name, Type>>

            SortedList<string, SortedList<string, Type>> myTypeList =
                ExtractListOfTypes(Assembly.GetExecutingAssembly());

            DumpTypeList(myTypeList);
        }

        private static SortedList<string, SortedList<string, Type>> ExtractListOfTypes(Assembly assem)
        {
            SortedList<string, SortedList<string, Type>> theList =
                new SortedList<string, SortedList<string, Type>>();

            foreach (Type t in assem.GetTypes())
            {
                // Add namespace if it's not already in list
                if (!theList.ContainsKey(t.Namespace))
                    theList.Add(t.Namespace, new SortedList<string, Type>());

                // And add type under appropriate namespace
                theList[t.Namespace].Add(t.FullName, t);
            }

            return theList;
        }

        private static void DumpTypeList(SortedList<string, SortedList<string, Type>> theList)
        {
            foreach (KeyValuePair<string,SortedList<string,Type>> kvp in theList)
            {
                Console.WriteLine(string.Format("Namespace: [{0}]", kvp.Key));

                foreach (KeyValuePair<string, Type> kvpInner in kvp.Value)
                {
                    Console.WriteLine(string.Format("  Type: [{0}]", ((Type)kvpInner.Value).FullName));
                }

                Console.WriteLine();
            }
        }

727-001

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#726 – Listing all Types within a Namespace

You can’t directly list out all types within a namespace.  But you can get all types within a particular assembly and then filter out only the types that match a particular namespace.

        static void Main()
        {
            // Dump all types from in a specified namespace
            DumpTypesForNamespace(Assembly.GetExecutingAssembly(), "ConsoleApplication1");
            DumpTypesForNamespace(Assembly.GetExecutingAssembly(), "ConsoleApplication1.Dog");

            int i = 1;
        }

        private static void DumpTypesForNamespace (Assembly assem, string theNamespace)
        {
            Console.WriteLine(string.Format("[{0}]", theNamespace));

            foreach (Type t in assem.GetTypes())
            {
                if (t.Namespace == theNamespace)
                {
                    string dump =
                        string.Format("{0}\n  ({1} in {2})\n", t.FullName, TypeIndicator(t), t.Namespace);

                    Console.WriteLine(dump);
                }
            }
            Console.WriteLine("\n");
        }

        private static string TypeIndicator(Type t)
        {
            string typeIndicator = "?";

            if ((t.BaseType != null) &&
                (t.BaseType.FullName == "System.MulticastDelegate"))
                typeIndicator = "delegate";

            else if (t.IsClass)
            {
                if (t.IsNested)
                    typeIndicator = "Nested class";
                else
                    typeIndicator = "class";
            }
            else if (t.IsInterface)
                typeIndicator = "interface";

            else if (t.IsValueType)
                typeIndicator = "struct";

            else if (t.IsEnum)
                typeIndicator = "enum";

            return typeIndicator;
        }

726-002

#523 – The using Directive Allows Omitting Namespace

A typical C# program will use types that are defined in a variety of namespaces.  Specifying the fully qualified type name that includes the namespace can become tedious.

using directive tells the compiler what namespaces to look for types in, avoiding the need for fully qualified type names.

Assume that we have a Dog type, defined in the DogLibrary namespace.  The fully qualified type name is DogLibrary.Dog.  But in the code fragment below, we can just use Dog as the type name, because of the using directive.

using DogLibrary;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main()
        {
            Dog kirby = new Dog();
            kirby.Bark();
        }
    }
}

So you can use a type name without its namespace if:

  • The type is defined in the same namespace as the current code
  • using directive for the type’s namespace is present

#521 – Namespaces Help Organize Types

In C#, a namespace is a collection of related types.  The fully qualified name of every type actually includes the namespace that it’s defined in.

You use the namespace keyword to define a namespace.  All types defined within the pair of braces that follow the namespace name then belong to that namespace.

In the example below, the Dog class belongs to the DogLibrary namespace.

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

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

Because Dog is defined within the DogLibrary namespace, the fully qualifed name of the Dog type is DogLibrary.Dog.

#6 – An Even Smaller C# Program

In The Smallest Possible C# Program, I mentioned a couple things as optional.  For the record, here’s the absolute smallest C#.NET program that you can write.  (Assuming that you don’t need it to actually do anything).

class Program
{
    static void Main()
    {
    }
}

#2 – The Smallest Possible C# Program

The smallest possible C# program would consist of a static Main() function inside of a class. The namespace is actually optional, as is the args parameter.

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("2,000 Things Was Here..");
        }
    }
}