User Defined Attributes

[Sönke Ludwig]

Wow, that's a surprise! Just yesterday I was thinking that it would be
really nice to have them for a piece of code ;)

But shouldn't we keep the syntax closer to normal attributes and other
languages(*)? I see a lot of arguments for doing that, with the only
counter-argument that they would be in the same namespace as the
built-in attributes (which should not be that bad, as this is very low
level language stuff).

(*) i.e. @mytype or @("string") and without the '[]'