Sorting custom component input by type.

Thought this was rather a simple problem, but it's obviously not!

This works fine inside a c# component: 

private void RunScript(List<System.Object> OBJ, ref object A)
{

foreach(System.Object myObj in OBJ)
{

if(myObj is Mesh) {...} else if(myObj is Curve) {...} else if(myObj is Point3d) {...}

}

Nevertheless, reproducing this inside a custom component seems to elude my powers...

Any hints, tips and tricks? I'm banging my head on this since quite a while...

Cheers!