c# - Nullable problems with Activator.CreateInstance and Convert.ChangeType -

i have third party library sets given objects property using reflection follows. (this simplified version)

public void set(object obj, string prop, object value) {     var propinf = obj.gettype().getproperty(prop);     value = convert.changetype(value, propinf.propertytype);     propinf.setvalue(obj, value, null); } 

and have class nullable property

class test {     public int? x { get; set; } } 

when write following code, says cannot convert int int?

var t = new test(); set(t, "x", 1); 

since nullable not implement iconvertible makes sense. decided write method returns nullable version of given value typed object.

public object makenullable(object obj) {     if(obj == null || !obj.gettype().isvaluetype)         throw new exception("obj must value type!");      return activator.createinstance(         typeof(nullable<>).makegenerictype(obj.gettype()),          new[] { obj }); } 

i hoped use method follows.

var t = new test(); set(t, "x", makenullable(1)); 

but still says cannot convert int int?. when debug typeof(nullable<>).makegenerictype(obj.gettype()) equals int? activator.createinstace returns int value not int?

so case... help?

this should work:

public static object changetype(object value, type conversiontype) {    if (conversiontype.isgenerictype && conversiontype.getgenerictypedefinition() == typeof(nullable<>))    {        if (value == null)            return null;        var nullableconverter = new nullableconverter(conversiontype);        conversiontype = nullableconverter.underlyingtype;     }     return convert.changetype(value, conversiontype);  }