Adding generic constraints at runtime?

Question

I'm pretty stumped with this so if anyone has any ideas. I have the generic method

public void Foo<TClass>(TClass item) where TClass : class
{ }

And I want to call this method from another generic method, but this generic method doesn't have the type constraint "where TClass : class"

public void Bar<T>(T item)
{
    this.Foo<T>(item);
} 

This doesn't work, I get the error

"The type 'T' must be a reference type in order to use it as parameter 'TClass'"

Which I understand. But my question is this - is there anything I can do with C# syntax in order to "filter" the generic type "T" to pass it to "this.Bar" if it is a class. Something like....

public void Bar<T>(T item)
{
    if (typeof(T).IsClass)
        this.Foo<T **as class**>();
} 

I realise I could use reflection to call Foo, but this just seems like cheating. Is there something I can do with C# to pass "T" on with the constraint at runtime?

Also - I can't change the constraint on the method "Bar" as it comes from an interface so the constraint has to match the constraint on the interface

Answer 1

The only way to call Foo without reflection, is to cast item to one of the types/classes in its hierarchy (after the proper IsClass check).

Obviously, there's only one type in its hierarchy that you know of a priori: Object.

public void Bar<T>(T item)
{
    if (typeof(T).IsClass)
        this.Foo((object) item);
} 

Edit :

Also, in one of the comments you said you added the class constraint to be to instantiate T. You don't need that, what you need is the new constraint.