Question

I have a class declared as such:

public abstract class CrmAttribute <T> : ICrmAttribute
{

}

And in one of the methods further down I have this

castedValue = (T)value;

castedValue is then used in other methods of type T as a parameter.

My problem is a case has come up such that the above cast throws an InvalidCastException.

From what I can tell this is one specific case; In Dynamics 2011 Microsoft finally moved away from custom types like CRMNumber and moved to inherent .Net types but not for all cases. Of the ones that remain, is a complex Money type that has one property of .Value which contains a decimal. This is where my Exception is thrown as I cannot cast a decimal to a Money type. Even though a Money object is essentially a Decimal.

I’m still fairly new to generics and much of this is inherited code so I’m well aware the correct response is to not do this per se, But all I want to do is to be able to create my own implicit cast of type Money to Decimal so that the line using T will cast correctly.

Is this possible?

Answer 1

Your best bet is to add code to your class around the cast to test if T is the problematic type and perform the appropriate conversion instead of relying on cast.

Perhaps something like this:

if (typeof(Money).IsAssignableFrom(typeof(T))
{
    // special handling required to convert decimal to money
    castedValue = new Money() { Value = value };  // ? best guess
}
else
{
    castedValue =(T)value;
}