[Qemu-devel] Re: [PATCH 00/15] QAPI Round 1 (core code generator) (v2)

[Paolo Bonzini]

On 03/16/2011 03:34 PM, Luiz Capitulino wrote:
> +##
> +# @put_event:
> +#
> +# Disconnect a signal.  This command is used to disconnect from a signal based
> +# on the handle returned by a signal accessor.
> +#
> +# @tag: the handle returned by a signal accessor.
> +#
> +# Returns: Nothing on success.
> +#          If @tag is not a valid handle, InvalidParameterValue
> +#
> +# Since: 0.15.0
>
> The name 'signal' (at least today) doesn't make sense on the wire protocol,
> 'put_event' probably doesn't make sense in the C library, nor does 'event'.
>
> Another detail is that, event extension is more important than command
> extension, because it's probably going to happen. I think it would be very
> bad to add new events just because we wanted to add a new field.

What if events were always passed a single struct, with the first field 
being a bitmask saying which (or how many) fields have been filled?

It is quite ugly to work that way when calling functions, but it's not 
too bad when you are writing the callees.  And it's the code generator 
that writes the function calls in the case of libqmp...

Paolo