c# - 如何在 C# 中调用 protected 构造函数？

Question

如何调用 protected 构造函数？

public class Foo{
  public Foo(a lot of arguments){}
  protected Foo(){}
}
var foo=???

这显然没有通过测试:

public class FooMock:Foo{}
var foo=new FooMock();
Assert(typeof(Foo), foo.GetType());

Answer 1

调用无参数保护/私有(private)构造函数:

Foo foo = (Foo)Activator.CreateInstance(typeof(Foo), true);

调用带参数的非公共(public)构造函数:

  var foo = (Foo)typeof(Foo)
    .GetConstructor(
      BindingFlags.NonPublic | BindingFlags.CreateInstance | BindingFlags.Instance, 
      null, 
      new[] { typeof(double) }, 
      null
    )
    .Invoke(new object[] { 1.0 });

  class Foo
  {
     private Foo(double x){...}
  }