Re: [Qemu-devel] [PATCH 6/9] QError: Add qdev not found error

[Anthony Liguori <aliguori@us.ibm.com>]

Gerd Hoffmann wrote:
>   Hi,
>
>> { "error": { "code": 404,
>>               "desc": "husb: host usb device 0.12 is already open" } }
>>
>>   In case I'm right, there are two problems with it:
>>
>> 1. It's hard to retrieve the variable information
>
> Markus asked it already, I'm asking again:
>
> *Do we actually need the variable information?*
>
> The point is that the information usually is available from context 
> anyway, i.e. if you get the reply above from a command like 'usb_add 
> host:0.12' you know it is host device 0.12 *without* parsing reply 
> because you know you've asked for host device 0.12.

I would recommend treating errors like exceptions.  In fact, if I were 
writing a python client library, this is exactly how I would model it.

In fact, it would make sense to switch code to some sort of class name.  
This would be the exception class.  The data argument would be the 
exception object.  desc would basically be __str__() method although 
more limited.

Very often, exceptions have very little data associated with them.  
Sometimes it's useful to include a bit of info though.

-- 
Regards,

Anthony Liguori