Question

I’m trying to load and use a DLL at runtime and this works fine:

var pluggin = asm2.CreateInstance("ParserTest.Interface", true) as iPluggin;

But this doesn’t (I need to loop through the DLL files in a specific folder to find the right ones implementing iPluggin interface):

...
var asm = Assembly.LoadFrom(dll.FullName);
if (asm.GetExportedTypes().FirstOrDefault(q => q.GetInterface(tName) != null) == null) continue;
Project.ProcessList.Add(asm.CreateInstance(tName, true) as iPluggin);
...

Doing some research in debug mode I found out that:

asm.CreateInstance(tName, true)

returns the correct object, but when trying to cast it to iPluggin the result is null.
Any idea why?

Answer 1

Mistery solved althought I don’t understand it.

The DLL that defines de interface (SDK.dll) was among the ones being checked.
I removed it manually in my query and all woks as expected now.
This is my final code:

    var plugins =
        from fi in di.GetFiles("*.dll").Where(p => p.Name.ToUpper() != "SDK.DLL")
        let asm = Assembly.LoadFrom(fi.FullName)
        from t in asm.GetExportedTypes()
        where t.GetInterface(typeof(iPluggin).Name) != null
        select asm.CreateInstance(t.FullName, true) as iPluggin;
    Project.ProcessList.AddRange(plugins);