From: John Torjo (john.lists_at_[hidden])
Date: 2005-11-14 08:51:27
> Some main thoughts:
> 1) It might be helpful if loggers and managers were "promoted" to
> objects with an obvious interface that can be easily passed around.
Managers will be promoted to objects.
Perhaps loggers can be promoted too.
> 1.1) I haven't had a problem passing loggers around by use using a
> logger& or a logger*, but the interface seems to assume that generally
> the code will be compiled where the log name is known. Most of the code
> I work on is header or dll code that needs to be passed a logger by the
> main system.
Not sure I follow...
> 1.2.1) I think the static manager makes the design harder to use and
> control in a system that isn't a single executeable. This could be
> solved by either forcing the user to declare the manager, or possibly by
> leaving it static, but making all the functions take an explicit manager
> ref or pointer, or making the functions members of the manager.
If you take a look at log_manager.hpp, you'll see that this is how it
happens now. Or have I misunderstood something?
> 18.104.22.168) The static manager seems particularly problematic for dlls.
> 22.214.171.124.1) Currently, the dll can't call the api functions and act on
> the application's logs, since the calls will be compiled to act on the
> dll's static log manager (I think). Although "externally visible" is a
> design premise of the library, I don't think the dll can even enable or
> disable application logs it knows the name for because the call will go
> to its own logs of the same name. Similarly the application can't
> control the dlls logs for the same reason... I think!... maybe I missed
> how to do this. If that's the case maybe the doc just needs to be more
The docs need to be more extensive on this issue ;)
> 126.96.36.199.2) It looks like there could actually be multi-threaded issues
> writing to logs from a dll, because, if the log thread is used, both the
> dll and the app will start their own trhead to write to the log.
> Presumably the log is ultimately a single object, like the screen or a
> file. I suppose if the locking uses a "named" lock that the OS api can
> look up this could be solved. However, it looks like on windows at least
> a Critical Section is used, which I don't think is named, so I don't
> think the one or more dlls running the thread and the application would
> actually lock each other. It seems like they could step on each other.
If you specify the appenders/modifiers only in one place (like, in the
Executable), there are no problems.
> 1.3) I can't seem to pass around log levels. I think this is because
> they are const ints, not members of an enum. This means the following
> code won't compile:
> void SomeClass::Dump(boost::logging::level_type eLevel,
> boost::logging::logger& rLog)
> BOOST_SCOPEDLOGL(rLog, eLevel)
> << "Some Msg" << m_iSomeMemberVariable << endl;
At this time, indeed you can't.
I'll find a solution.
In particular, log levels can't be members of an enum, since you should
be able to add your own at any time.
> 2) BOOST_LOG and BOOST_SCOPEDLOG are way too many uppercase characters
> to type. :)
Well, you're right :) But so far can't think of any names that could be
> >> - What is your evaluation of the implementation?
> Looks fine. No usage headaches. Find a few minor bugs, to be expected.
> No major ones.
> >> - What is your evaluation of the documentation?
> Good start, but as usual, could use more - John we know you need more
> work :). In particular, I think some description of the underlying
> implementation would be helpful. I'd like to see a description of the
> major objects and their data structures, and their relation to each
> other. I'd like to see a description of how "add_appender" works. It
> took me a while to struggle through this in the code.
> In particular, I'd like to see a description of how exactly the
> BOOST_LOG macro works! This is the most important part of the libary,
> and there are couple indirections an inversion in the implementation,
> (which seems fine), but takes a bit to understand.
> John, I can volunteer some hours in next couple weeks to help review or
> add doc if you like. If that would be helpful, I just need some
> direction files to review or subject matter. You can e-mail me at "a dot
> schweitzer dot grps at gmail dot com"
I'll definitely call you on that!
Andrew, was this a formal review? I'm asking, since I did not see the
"Yes" (accept) or "No" (reject) at the end of it.
-- John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/surfaces.html - Sky's the limit! -- http://www.torjo.com/cb/ - Click, Build, Run!
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