Using an expression is probably fine for now, especially for consistency as other attributes are parsed the same, but I think that at some point we should instead have specific structs to describe attributes in a less obfuscated way.
This is a good idea, but perhaps it would be better to add it after moving to IDL 3.0, well if we move to it anyway.
Note also that I've started to progressively convert this file to using spaces only, and to use julliard style spacing too for readability. Tabs alignment gets often messed up and will look differently depending on the editor settings.
The editor I use converts tabs to spaces. I'm not really sure what constitutes julliard style spacing, but if it's like the style in the WinRT DLLs then that's something I appreciate. It definitely makes readability a lot better.
Anyway, I hope this was the formatting you wanted.
Thanks for the reviews!