On 08/27/2010 03:49 PM, Steven Schveighoffer wrote:
On Thu, 26 Aug 2010 18:19:24 -0400, Tomek Sowiński <[email protected]> wrote:
Dnia 26-08-2010 o 05:59:19 Andrei Alexandrescu
<[email protected]> napisał(a):
At my workplace we're using Google's logging library glog
(http://google-glog.googlecode.com/svn/trunk/doc/glog.html), and the
more I use it, the more I like it. It's simple, to the point, and
effective.
I was thinking it would be great to adapt a similar design into
Phobos. There will be differences such as use of regular argument
lists instead of << etc., but the spirit will be similar. What do you
think?
Hm.. why not. Some quick thoughts:
* Only a subset of features needs to be ported, e.g.
DLOG(...) == version(debug) LOG(...)
CHECK == enforce()
Also, I don't get the superlativeness of LOG_IF(INFO, pred) << ...
versus if (pred) LOG(INFO) << ...
I think I know why, without even looking at the code. A typical issue
with logging is that you want to evaluate the log output level, which is
always an O(1) operation, before evaluating any other items which may be
expensive, such as a custom predicate or message.
i.e. LOG_IF probably does this:
if(log.level >= INFO && pred)
This is one of the only reasons I think we need a macro system. Mixins
can do this, but who wants to always write mixin when doing logging?
lazy is traditionally used, but it has costs as well. The best solution
is to have a macro that converts:
log.info(msg);
directly into:
if(log.level >= info) log.output(msg);
which doesn't require lazy and is exactly what you *should* write.
* Instead of LOG(INFO, msg), please go for Log.info(msg).
Most likely, this is due to the same thing.
-Steve
Since lazy is rarely needed, one could use non-lazy by default and have
a lazy as well, like log.info.lazy(msg) or equivalent.
