How to provide conversion when using Reflection.SetValue?

Question

I have a class that pretends to be an int, so it has overloaded the various operators;

public class MyId
{
    int value;
    public virtual int Value
    {
         


        

Answer 1

Implicit conversions are a C# construct and are not available through reflection. Additionally, setting a field or property through reflection means that you must provide the appropriate type up front. You can attempt to circumvent this by using a custom TypeConverter (or some other means of custom conversion) to help convert your types at runtime prior to using reflection. Here's a rough example of a TypeConverter implementation.

public class MyIdTypeConverter : TypeConverter
{                
    public override object ConvertFrom(ITypeDescriptorContext context,
                                       System.Globalization.CultureInfo culture,
                                       object value)
    {   
        if (value is int)
            return new MyId((int)value);
        else if (value is MyId)
            return value;
        return base.ConvertFrom(context, culture, value);
    }               
}

Here's the type that we would be trying to set the Custom property on.

public class Container
{
    [TypeConverter(typeof(MyIdTypeConverter))]
    public MyId Custom { get; set; }                
}

The code to call it would have to check the attribute and perform the conversion ahead of time, after which it could call SetValue.

var instance = new Container();
var type = typeof(Container);
var property = type.GetProperty("Custom");

var descriptor = TypeDescriptor.GetProperties(instance)["Custom"];
var converter = descriptor.Converter;                
property.SetValue(instance, converter.ConvertFrom(15), null);