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Message-ID: <4AFB2A9E.9050309@codemonkey.ws>
Date: Wed, 11 Nov 2009 15:20:30 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [RFC 0/8]: QError v2
References: <1257365047-25895-1-git-send-email-lcapitulino@redhat.com>
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To: Luiz Capitulino <lcapitulino@redhat.com>
Cc: pbonzini@redhat.com, aliguori@us.ibm.com, qemu-devel@nongnu.org, hollisb@us.ibm.com, kraxel@redhat.com

Luiz Capitulino wrote:
>  Hi,
>
>  I can't remember seeing updated versions of a RFC series, but this should
> prevent Anthony's scripts from merging these patches.
>
>  This new QError version has two major changes: the static error table has
> been dropped and I'm using symbolic names instead of error codes.
>
>  Now, a call to:
>
> monitor_printf(mon, "husb: host usb device %d.%d is already open\n",
>                bus_num, addr);
>
>  Would become something like:
>
> qemu_error_new('DeviceAlreadyOpen', "{ 'bus_num': %d, 'addr': %d }",
>                bus_num, addr);
>   

I mostly like this but this is not what the patches do :-)

Here's what I would like to see:

#define QERR_DEVICE_ALREADY_OPEN "{'class': 'DeviceAlreadyOpen', 'data' 
: {'bus_num': %d, 'addr': %d}"

qemu_error_new(QERR_DEVICE_ALREADY_OPEN, bus_num, addr);

That gives us a nice simple interface with full error checking on the 
parameters.

For human readable strings, I'd suggest making a table somewhere else 
that looked like:

QErrorStringTable qerror_descriptions[] = {
{ QERR_DEVICE_ALREADY_OPEN, "This device at %(bus_num)d.%(addr)d is 
already open." },
...
};

There are a number of advantages to an approach like this.  The table 
can be reused by both in the server and by a client.

Regards,

Anthony Liguori