Unable to call set_result_subtype at the appropriate time

[mullr]

I see that you have added a binding for sqlite3_result_subtype, which is great, that's exactly the thing I need! However, this needs be called /after/ sqlite3_result_* in order to take effect, which isn't currently possible.

Do you have something in mind for how to do it? I'd be happy to implement it if it's reasonably straightforward.

[mullr]

I've hacked around this over at https://github.com/mullr/rusqlite/tree/set_result_hack by adding a FunctionFlag value to ignore the return value of the user provided function. I also exposed set_result on Context, so user code can call set_result and then set_result_subtype.

As the branch name suggests, this not that nice. But maybe it's ok? The surrounding types don't leave much room for maneuvering without some pretty major surgery, afaict.

[gwenn]

What about:

pub trait SubType : ToSql {
   fn sub_type(&self) -> Option<c_uint> {
     None
   }
}

?

[mullr]

That seems like a great API. It would either require that the create_*_function calls use that as a type constraint instead of ToSql, breaking existing users, or adding new variants of create_*_function that allow this type. Is one of those preferable?

[gwenn]

@mullr Could you please check #1160 ?

[mullr]

@gwenn #1160 looks good to me. Thanks for putting that together!

[gwenn]

Version 0.31.0 released