[boost] Re: recommend logging library?

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2004-03-19 02:59:48

Mark Blewett wrote:
>> I think it's the wrong approach. In our company we have implemented 
>> logging through macros which has one very important property: When I 
>> write
>>
>> LOG_DEBUG( whatever() );
>>
>> into my source, then whatever() is only evaluated when the 
>> debug-logger is active. The macro basically expands to something like 
>> this:
>>
>> if( Base::hasLogger( LogLevel::DEBUG ) )
>>   Base::log( whatever(), LogLevel::DEBUG );
>>
>> I think this cannot be done without macros as normal function calls 
>> (including operator<< for streams) need to evaluate their arguments 
>> before they are called. As the difference in the application execution 
>> speed can vary by a factor of 1000, this is a very valuable 
>> optimization for us. My 2¢.
> 
> 
> Personally I think restricting boost to disabling logging on a #define 
> is a double negative... ie a no no.

You misread what I wrote. Logging is disabled through the return value 
of hasLogger(), which can be modified at any time. When hasLogger() 
returns false, the expression whatever() is never evaluated, which is 
the important part. The macro never removes the code itself (well, it 
could, but we never needed it so far).

Regards, Daniel

-- 
Daniel Frey
aixigo AG - financial solutions & technology
Schloß-Rahe-Straße 15, 52072 Aachen, Germany
fon: [phone], fax: [phone]
eMail: daniel.frey_at_[hidden], web: http://www.aixigo.de