Announcing new version of the Qt4 bindings

Daniel P. Berrange dan at
Tue Feb 14 06:05:44 PST 2006

On Tue, Feb 14, 2006 at 11:42:24AM +0100, Thiago Macieira wrote:
> Havoc Pennington wrote:
> >Did you find any "this should really be fixed for 1.0" kind of issues in
> >doing your bindings, btw?
> I remembered two more things I consider to be a problem, but would fall 
> into the "nice to have" category.
> 1) The org.freedesktop.DBus.UnknownMethod reply is too broad.
> When we receive a reply like that, we don't know if:
> - the called object didn't exist
> - the called object exists, but there is no such interface on it
> - the called object and interface exist, but there's no such 
> method-signature on it

Yes, I agree with that idea - when writing & debugging the Perl bindings
I came to the opinion that it would be useful if there was a standard set
of error names to be used for specific conditions. IIRC, there's probably
around 5-10 different conditions you'd want to identify. Doing this would
let the client side bindings provide much more informative error messages
to developers.

> 2) [related to 1] There's no way of telling if a remote object exists. 
> Even by introspecting it, if we get an UnknownMethod reply, we don't know 
> if the object doesn't exist or if it doesn't allow introspection. If we 
> try to ping it, we'll always get a success, because libdbus catches the 
> message.

This is another aspect of an issue that's been brought up a couple of 
times before  - namely the question of how to get a list of 'root' objects
exported by a service. 

> The problem with fixing #1 would be that the API would change: the result 
> from the filters wouldn't be "handled / not handled", but would have to 
> indicate the reason why it didn't handle.

Couldn't the remote service just return 'handled', but send back a error
message instead of a method reply for all these cases ?

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