From: Charles Oliver Nutter <charles.nutter@...>
Date: 2008-11-11T13:52:44+09:00
Subject: Re: [ANN] FFI 0.1.1 (Foreign Function Interface) for Ruby 1.8.6/7 and 1.9

Clifford Heath wrote:
> Charles Oliver Nutter wrote:
>> Actually structs are already supported!
> 
> Sorry if you see this twice, posting difficulties.
> 
> I'm having a bash at wrapping freetds. This library
> has a Context struct which contains three callback
> function pointers. POLS says these should look like
> this:
> 
> callback :handle_message, [ :pointer, :pointer, :pointer ], :in   # 
> TDSCONTEXT, TSSSOCKET, TDSMESSAGE
> callback :handle_int, [ :pointer ], :in     # void*
> 
> class Context < FFI:Struct
>   layout \
>     :locale, :pointer, 0,                   # TDSLOCALE
>     :parent, :pointer, 4,                   # void *
>     :msg_handler, :handle_message, 8,       # callback(TDSCONTEXT, 
> TDSSOCKET, TDSMESSAGE)
>     :err_handler, :handle_message, 12,      # callback(TDSCONTEXT, 
> TDSSOCKET, TDSMESSAGE)
>     :int_handler, :handle_int, 16           # callback(void*)
> end             
> Am I on the right track, or is this not possible yet?

There's no support at the moment for callbacks-in-structs, but it's just 
a bug report (and ideally a patch) away :)

http://kenai.com/projects/ruby-ffi

- Charlie