Re: [boost] logging v1.4 - some comments

From: John Torjo (john.lists_at_[hidden])
Date: 2005-08-18 08:49:11

Darryl Green wrote:
> Excuse the break in threading - gmane has lost/missed a lot of boost traffic.
> 
> Hi John,
> I've only had a quick look at the latest version:
> 
> The m_destroyed hack needs to go - this should only be relevant for static (not 
> scoped) logs and the real issue is that you need to do thread-safe singletons - 
> ie. you need to use posix call_once or equivalent to contstruct the thing. 
> Destruction is a bit tricky - not doing it seems a reasonable option, though 
> stopping leak detectors from compaining would be nice.

I don't think construction is tricky. I think knowing whether I'm still 
constructed - that's the problem. And for scoped logs, you can simply 
ignore it.

> 
> The scoped log stuff doesn't seem to have been updated to support levels yet - 
> in fact I'm not sure if it currently works?

It does work, and it does support levels: BOOST_SCOPEDLOG and 
BOOST_SCOPEDLOGL

> 
> I think (fancy that - given the way it was in analog ;-)) that the named 
> appenders need to be managed - currently, you can create multiple appenders 
> with the same name, then when you delete by name you delete all appenders with 
> that name. I don't see the utility of that model, which when combined with the 
> wildcard matching is really fairly hard to use. For example, suppose I have an 
> appender that logs to some sort of display for "real time" tracing. First off, 
> I say:
> 
> manipulate_logs("error.*").add_appender(displaywrite, "display")
> 
> Then I notice an error about some component foo and decide to look at more 
> detail about foo:
> 
> manipulate_logs("*.foo").add_appender(displaywrite, "display")
> 
> Now I get anything logged to "error.foo" written to "display" twice.
> 
> I then say:
> 
> manipulate_logs("error.*").del_appender("display")
> 

You're right. What comes to mind, is to have an extra parameter:
bool add_even_if_name_exists.

So, if passing 'false', if "display" already exists, it's not added. If 
passing 'true', "display" is added even if it exists.

Best,
John

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John Torjo,    Contributing editor, C/C++ Users Journal
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