Re: [boost] Re: Re: logging library?

From: John Torjo (john.lists_at_[hidden])
Date: 2004-04-19 12:45:16

>Is it? The basic idea is 
>(1) to have functional object to do the logging
>(2) allow to form chain of responsibility pattern from individual objects to
>make the system for flexible.
>
>  
>
this can be implemented within the log function, if it's really necessary.
I don't see why it would need to be too formal.

>>Here's how I see it:
>>1. Given a log level, the user gets hold of the corresponding
>>boost::logger and tries to output something.
>>    
>>
>
>I think that hierarchical loggers ala log4j are necessary.
>
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Yes, they are, and I will certainly implement them.
Each type of log will have a unique internal ID, by which you use it 
within your program
(example: LOG(activity) << "blabla")
and a string associated with it (example: "app.activity").

Based on this hierarchy the message will be forwarded to a certain function.
Also, enabling/disabling of logs can happen like this: logs().disable( 
"*.warn.*"); // disable all warning messages

>>2a. If that log is disabled, nothing else happens.
>>2b. If that log is enabled, the message to be outputted is written to a
>>stringstream, then
>>    converted to a string..
>>    The function corresponding to its level is called. That's it!
>>    
>>
>
>What I propose is that this function can forward the request (after some
>processing) to other functions. In other words, you focus on front-end
>interface while I talk about inner workings.
>
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yes

>>If you want formatter (your step 5.) or prefix (your step 4.), you can
>>simply do them in your custom function.
>>    
>>
>
>It simpler (IMO) to write
>
>    syslog_appender sl;
>    file_appender fl;
>    timestamp_adder t;
>    t.message.connect(sl);
>    t.message.connect(fl);
>    your_logger.message.connect(timestamp);
>
>  
>
haven't used boost::signals before, but I guess I know what you mean.
I'll definitely think about it...

>that to write a custom function do to the same. Further, with a custom
>function you cannot customize the processing chain from config file.
>
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you can do basically anything with a custom function (if you wish:D)
As with the config file, if anyone wants to specify processing chain
in a config file, they will implement it on top of my log library.
I don't intend to provide working with a config file from the log 
library - that would be too much coupling.

>Besides, I think configuring loggers from config file is a very good thing,
>too.
>  
>

Yes, me too (mostly enabling/disabling). But, you should use another 
library to read from the config file (for instance: Persisting Settings 
Library (http://builder.com.com/5100-6370-5157525.html?tag=sc)), and 
then specify the logging options.

Best,
John

>- Volodya
>
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