Could syntax like this allow for nested partial types to be possible without the parent type being partial?

[nathanAjacobs]

The following syntax would allow source generators to support nested types easily without requiring the parent class to be declared partial.

// in File1.cs
namespace MyNamespace;

public class ParentClass
{
    private partial class NestedClass
    {
    }
}

// in File2.cs
namespace MyNamespace;

private partial class ParentClass.NestedClass
{

}

[CyrusNajmabadi]

Our view is that types must be marked partial. That way things cannot be added to them without that being an explicitly opted into thing.

[nathanAjacobs]

Would this not still satisfy that contract though? The only type that would be added to is the NestedClass which is marked partial.

The keywords would only apply to the type after the last '.'

[CyrusNajmabadi]

You'd be adding a member to the outer type in another file. We intentionally make that something the outer type needs to opt into :-)

[jnm2]

@CyrusNajmabadi I'd say that the outer type already opts into this, at the granularity of the nested type only, by virtue of the fact of including the partial keyword on its declaration of the nested type.

[CyrusNajmabadi]

oh, i see. i missed that the original decalration was opting in. That does change things a bit. That said, the motivation of "would allow source generators to support nested types easily" is less compelling to me as i don't think it's particularly hard to get SGs to support nested types in the first place.

[nathanAjacobs]

@CyrusNajmabadi It can be done with source generators currently, but it requires the whole type tree to be partial, whereas this would only require the nested type to be partial.