2009/11/14 John Croisant <jacius@gmail.com>:

> But, I thought you could use the enum name as a type, even in structs.
> I haven't tried it yet, but it certainly feels like that _should_ be
> supported, from a library user's perspective. Even if that doesn't
> work yet, "enum_type(:my_enum)" would work, right?

The problem is that Struct.layout() needs to be able to resolve the
module that encloses the Struct subclass definition, to be able to
lookup any custom typedefs (e.g. callbacks, enums).

e.g.
Module Foo
  typedef :int, :my_int
  class MyStruct < FFI::Struct
    layout :a, :my_int
  end
end

It kinda-sorta works, but is not rock solid, so I discourage its use.

> P.S. Does FFI enforce the validity of values used where a particular
> enum type is expected? In other words, if a function (or struct) is
> expecting an enum that can be only :a, :b, or :c, would passing :d
> cause it to raise an error?

Passing :d should raise an error, since it will try to look it up in
the enum table and fail.