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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.


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