使用反射在`this`类中查找私有字段，并将其实例化

Question

Hypothetical situation. Say I had a class which contained numerous private fields. I want it to instantiate every field that it can find with the correct type . So far, I have used

public class TestClass
{
    private SomeClass sc;
    private AnotherClass ac;

    public TestClass()
    {
        var type = GetType();
        var fields = type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
            .Select(x => x.Name)
            .ToList();

        foreach (var f in fields)
            type.GetField(f).SetValue(/*instantiate here*/);
    }
}

How would one instantiate it? (this is assuming the new() constructor in each class is parameterless and is not empty)

Answer 1

Activator.CreateInstance(Type) can create an instance from the type. This requires a parameter-less constructor (there are overloads for parameters).

To use it, just modify your code a little bit:

public class TestClass
{
    private SomeClass sc;
    private AnotherClass ac;

    public TestClass()
    {
        var type = GetType();

        type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
            .ToList()
            .ForEach(f => {
                f.SetValue(this, Activator.CreateInstance(f.FieldType);
            });
    }
}