Re: [Qemu-devel] [PATCH v3 1/2] monitor: cleanup parsing of cmd name and cmd arguments

[Eric Blake <eblake@redhat.com>]

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On 05/28/2015 12:48 PM, Bandan Das wrote:
> Markus Armbruster <armbru@redhat.com> writes:
> 
>> Bandan Das <bsd@redhat.com> writes:
>>
>>> There's too much going on in monitor_parse_command().
>>> Split up the arguments parsing bits into a separate function
>>> monitor_parse_arguments(). Let the original function check for
>>> command validity and sub-commands if any and return data (*cmd)
>>> that the newly introduced function can process and return a
>>> QDict. Also, pass a pointer to the cmdline to track current
>>> parser location.

>>>  
>>>  #ifdef DEBUG
>>> -    monitor_printf(mon, "command='%s', start='%d'\n", cmdline, start);
>>> +    monitor_printf(mon, "command='%s', start='%d'\n", cmdline, *start);
>>
>> Would this compile if we defined DEBUG?
> 
> No, it won't :) Sorry, will fix.

That's why I like solutions that can't bitrot; something like this
framework (needs a bit more to actually compile, but you get the picture):

#ifdef DEBUG
# define DEBUG_MONITOR 1
#else
# define DEBUG_MONITOR 0
#endif
#define DEBUG_MONITOR_PRINTF(stuff...) do { \
    if (DEBUG_MONITOR) { \
         monitor_printf(stuff...); \
    } \
} while (0)

then you can avoid the #ifdef in the function body, and just do
DEBUG_MONITOR_PRINTF(mon, "command='%s'....) and the compiler will
always check for correct format vs. arguments, even when debugging is off.

Of course, adding such a framework in this file would be a separate
patch, and does not have to be done as a prerequisite of this series.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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