How to call a Managed DLL File in C#?

Question

I am making a scripting language but I have a serious problem.

I need to make it so you can call .NET DLLs in the language but I have found no way to do this in C#.

Does any one know how can I load and call a .NET dll programmatically? (I can not just Add reference so don't say that)

Because I it is for a scripting language , the user needs to be able to call any DLL that is placed in the same directory as the interrupter — Grunt, Jul 26 '11 at 13:22

score 5 · Accepted Answer · answered Jul 26 '11 at 13:31

5

Here's how I did it:

Assembly assembly = Assembly.LoadFrom(assemblyName);
System.Type type = assembly.GetType(typeName);
Object o = Activator.CreateInstance(type);
IYourType yourObj = (o as IYourType);

where assemblyName and typeName are strings, for example:

string assemblyName = @"C:\foo\yourDLL.dll";
string typeName = "YourCompany.YourProject.YourClass";//a fully qualified type name

then you can call methods on your obj:

yourObj.DoSomething(someParameter);

Of course, what methods you can call is defined by your interface IYourType...

answered Jul 26 '11 at 13:31

scrat.squirrel

3,607
26
31

It's sometimes a good idea to create a separate app domain for the loaded assembly which means you can throw it away once you're done. – Kev Jul 26 '11 at 13:59
How did you reference `IYourType` without referencing the DLL in the project? – Eric Omine Jun 02 '16 at 18:43

score 2 · Answer 2 · answered Jul 26 '11 at 13:23

You can use Assembly.LoadFrom, from there use standard reflection to get at types and methods (i assume you already do this in your scripting). The example on the MSDN page (linked) shows this:

Assembly SampleAssembly;
SampleAssembly = Assembly.LoadFrom("c:\\Sample.Assembly.dll");
// Obtain a reference to a method known to exist in assembly.
MethodInfo Method = SampleAssembly.GetTypes()[0].GetMethod("Method1");
// Obtain a reference to the parameters collection of the MethodInfo instance.
ParameterInfo[] Params = Method.GetParameters();
// Display information about method parameters.
// Param = sParam1
//   Type = System.String
//   Position = 0
//   Optional=False
foreach (ParameterInfo Param in Params)
{
    Console.WriteLine("Param=" + Param.Name.ToString());
    Console.WriteLine("  Type=" + Param.ParameterType.ToString());
    Console.WriteLine("  Position=" + Param.Position.ToString());
    Console.WriteLine("  Optional=" + Param.IsOptional.ToString());
}

score 1 · Answer 3 · answered Jul 26 '11 at 13:23

1

It sounds like you need to use one of the overloads of Assembly.Load (Assembly.Load at MSDN). Once you have dynamically loaded your assembly, you can use System.Reflection, dynamic objects, and/or interfaces/base classes to access types within it.

answered Jul 26 '11 at 13:23

JohnC

844
4
10

How to call a Managed DLL File in C#?

3 Answers3

Linked