Re: [boost] Re: logging library?

From: John Torjo (john.lists_at_[hidden])
Date: 2004-04-16 01:06:04

Rob Stewart wrote:

>From: John Torjo <john.lists_at_[hidden]>
>  
>
>>What I want is to create a simple correspondence from a log_id (a level) 
>>into a log function.
>>Having that, you can always say something like:
>>LOG(activity) << whatever... << std::endl;
>>
>>if 'activity' is turned off this nothing gets evaluated (yes, LOG is a 
>>macro ;))
>>    
>>
>
>But each invocation of operator <<() must be evaluated, if only
>to learn that the ostream is disabled, right?  That could amount
>to a lot of overhead or clients would need to write custom
>functions that return a string from a set of arguments to reduce
>the number of operator <<() invocations.
>
>Otherwise, it sounds useful.
>
>  
>
Not if the LOG macro is something like:

#define LOG(x) if(!is_log_enabled(x)) ; else x

Then, LOG(x) << "me " << me << " and you " << you << std::endl;
Writing will be evaluated only if is_log_enabled returns true.

Best,
John