Re: [boost] Re: recommend logging library?

From: Geoff Leyland (gley001_at_[hidden])
Date: 2004-03-22 04:00:22

On 22/03/2004, at 6:37 PM, John Torjo wrote:

> Geoff Leyland wrote:
>
>> Hi,
>>
>> Why not do something like
>>
>> my_log("this_module_logging_flag_notes") << "Doing something in 
>> this_module";
>> my_log("that_module_logging_flag_errors") << "Something went wrong in 
>> that_module";
>>
>> where a log object is either (depending on a compile time setting) a 
>> proxy for a stream or a not_logger than has
>>
>
> this is not such a hard thing to do ;) I've implemented some log 
> classes like this in the (far) past ;)
> But what you would actually want is an enumerator or something, so 
> that you can write things like:
>
> log<error>() << "some error";
> log<activity>() << "some activity";

That's not a bad idea!

I tend to work with the idea that either I want no logging at all, with 
no code generated, or that logging is built in and I'm prepared to take 
quite a hit for its overhead.  I like using strings for keys because 
I'm too disorganised to get all the enums I need in one place in a 
large project.
However I think in a lot of cases, string keys would be to heavy for 
the run-time decision "log or not", which needs to be quick, even if 
you're generating the (large) stream code.

Perhaps a log with a policy for setting how to decide whether to be on 
or off?

I have vague mis-memories of X "atoms" which might have been something 
like

void large_function(void)
{
   unsigned		activity_log(get_log_index("my_activity"));
   ...
   log(activity_index) << "blah";
   ...
}

Which means you get the indexes organised at run-time, but only suffer 
the map search once per file/module/dll or whatever.

cheers,
Geoff