C# Find All Derived Types From Assembly
I was always wondering if there is any method to find all derived types for the given type within an assembly. It would be handy to just pass either a class or an interface type and it will return me all its subs. I’ve come out with a method does that. It finds all the derived types of an given type. The given type could be a class(concrete or abstract) or an interface. The derived types could be class, struct or interface.
Here is the data structure that was used for testing,
From the data structure in the diagram, the tests have been covered with
- Find all the types that implement MyInterfaceI
- Find all the types that implement MyInterface
- Find all the class types that implement MyInterface
- Find all the class types that inherits abstract class MyClass2
- Find all the class types that inherits class MyClass3
var result = FindDerivedTypesFromAssembly(Assembly.GetEntryAssembly(), typeof(MyInterfaceI), false);
foreach (var type in result) Console.WriteLine(type.Name);
Console.WriteLine(“All implements MyInterface”);
result = FindDerivedTypesFromAssembly(Assembly.GetEntryAssembly(), typeof(MyInterface), false);
foreach (var type in result) Console.WriteLine(type.Name);
Console.WriteLine(“Only the classes implements MyInterface”);
result = FindDerivedTypesFromAssembly(Assembly.GetEntryAssembly(), typeof(MyInterface), true);
foreach (var type in result) Console.WriteLine(type.Name);
Console.WriteLine(“Only the classes inherits MyClass2″);
result = FindDerivedTypesFromAssembly(Assembly.GetEntryAssembly(), typeof(MyClass2), false);
foreach (var type in result) Console.WriteLine(type.Name);
Console.WriteLine(“Only the classes inherits MyClass3″);
result = FindDerivedTypesFromAssembly(Assembly.GetEntryAssembly(), typeof(MyClass3), false);
foreach (var type in result) Console.WriteLine(type.Name);
Output:
MyInterface
MyClass3
MyClass1
MyClass2
MyClass4
MyClass5
MyStruct1
All implements MyInterface
MyClass3
MyClass1
MyClass2
MyClass4
MyClass5
MyStruct1
Only the classes implements MyInterface
MyClass3
MyClass1
MyClass2
MyClass4
MyClass5
Only the classes inherits MyClass2
MyClass5
Only the classes inherits MyClass3
MyClass4
Here is the extension method does that,
{
if (assembly == null)
throw new ArgumentNullException(“assembly”, “Assembly must be defined”);
if (baseType == null)
throw new ArgumentNullException(“baseType”, “Parent Type must be defined”);
// get all the types
var types = assembly.GetTypes();
// works out the derived types
foreach (var type in types)
{
// if classOnly, it must be a class
// useful when you want to create instance
if (classOnly && !type.IsClass)
continue;
if (baseType.IsInterface)
{
var it = type.GetInterface(baseType.FullName);
if (it != null)
// add it to result list
yield return type;
}
else if (type.IsSubclassOf(baseType))
{
// add it to result list
yield return type;
}
}
}
Bugs or issues are much appreciated.
3 Responses to “C# Find All Derived Types From Assembly”
Comment from John
Time October 9, 2010 at 9:30 am
Thank you very much… saved a lot of time 
…
Comment from PokeADonkey
Time July 12, 2012 at 9:23 pm
Great article, very much appreciated.
Slight error in the examples though as they should read “Assembly.GetEntryAssembly().FindDerivedTypesFromAssembly(typeof(MyClass3), false)” given that FindDerivedTypesFromAssembly is an extension method.
Comment from Alexander
Time April 30, 2010 at 2:40 am
Well done.. Great utility