Re: [PATCH v4 04/12] libqos/qgraph: add qos_dump_graph()

[Eric Blake <eblake@redhat.com>]

On 10/28/20 12:51 AM, Thomas Huth wrote:

>>>> +#define GREEN(txt) (  \
>>>> +    "\033[0;92m" txt  \
>>>> +    "\033[0m"         \
>>>> +)
>>>
>>> I don't think this is very portable - and it will only make logs ugly to
>>> read in text editors. Could you please simply drop these macros?
>>>

> Sure, colored output is nice, but we certainly also need a way to disable
> it, e.g. if you want to collect the log in a file and then have a look at it
> in a text editor.

Agreed. GNU libtextstyle
(https://www.gnu.org/software/gettext/libtextstyle/manual/libtextstyle.html)
is a much more portable way to do colored output where it becomes easy
to enable/disable or even adjust the colors to user preferences.  Sadly,
it is GPLv3+, and thus unusable for qemu.  But the bare minimum that you
must have when making colored output gated on whether stdout is a
terminal (that is, any program that does color should have a
--color=off|auto|on command-line option, and that in turn implies
function calls rather than macros to properly encapsulate the decision
logic.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org