Compiler Error CS1109
Extension Methods must be defined on top level static classes, 'name' is a nested class.
Extension methods cannot be defined in nested classes.
Example
The following example generates CS1109 because the class Extension is nested inside the class Out:
// cs1109.cs
public class Test
{
}
static class Out
{
static class Extension
{
static void ExtMethod(this Test c) // CS1109
{
}
}
}