[Mono-dev] ChangeType for Nullable

[Martin Baulig]

On Wed, 2006-05-24 at 09:31 -0700, tut wrote:
> Also i'd like to know if one of next expressions should return true:
> 
> 1) typeof(int?).IsSubclassOf(typeof(Nullable<>))
> 2) typeof(int?).IsSubclassOf(typeof(Nullable))

Hello,

neither of these should return true.

2.) this is `System.Nullable' - ie. the non-generic static class - and
    of course, no type can be a subclass of that.

1.) and again, you're comparing two different things:
    typeof(int?) is an instantiated generic type while
    typeof(Nullable<>) is the corresponding generic type definition; so
    this doesn't work.

3.) typeof(int?).IsSubclassOf(typeof(Nullable<int>))
    would be correct - comparing two instantiated generic types - but
    typeof(int?) is actually an instance of Nullable<int> - and not
    a subclass of it.

4.) typeof(int?) == typeof(Nullable<int>)
    is true.

Martin