Hi Thomas,
Thanks for posting this message. I hope that several people will comment
on this important question.
We implemented a TMessageHandler class in Root 2.23 and the Root
functions
Error and Warning have already been interfaced to this message handler
as well as some important classes like TFile or TTree.
We are expecting more comments on this issue before embarquing
in additional developments.
I want to make a remark at this point, based on previous mails
by George Heintzelman and Christian Holm Christensen.
The MessageHandler is more general than an ExceptionHandler.
The ExceptionHandler can use the services of the Messagehandler.
Rene Brun
Thomas Hadig wrote:
>
> Dear Rooters,
>
> I learned from Rene, that several users/collaborations are thinking
> about a "global" ROOT messaging system. I have come up with a simple
> idea and would like know your opinion.
>
> I admit that the classes I use will not match the current definition.
>
> A message will go through TROOT to the message handler. The message
> handler will be set with
> TROOT->SetMessageHandler(TMessageHandler *)
> If the Message handler is not set (or set to 0), a "standard" message
> should be written to cout.
>
> There will be two kinds of messages:
> - "one-time" messages and
> - message that will appear more often.
> and several levels of messages
> - Debug messages
> - Informational messages
> - Warning messages
> - Error messages
> - Fatal messages
> -... (startup messages, etc....)
>
> The message level can be an enumeration TMessageLevel
>
> In the first case, the message will be send to TROOT with
> TROOT->SendMessage(Char_t *, TMessageLevel)
> and will be given to the message handler.
>
> In the latter case it should be possible to "register" the message with
> the handler.
> Int_t handler->Register(Char_t *, TMessageLevel)
> The handler then stores the message string and returns a
> (unique) message number a. The message will then be called with
> TROOT->SendMessage(Int_t a)
> or
> TROOT->SendMessage(Int_t a, Char_t *)
> where the longer version allows to make additional "output".
>
> The message handler can do with these messages, what he likes to do.
> A simple handler might only print the message. A more complex one
> will also count how often a register message occures and will be able
> to print a statistics at the end. Also a message handler might be
> able to suppress messages below a certain level or a set of levels.
>
> Examples:
>
> ofstream *errout = new ofstream("outputfile");
> TMessageHandler *h = new TMessageHandler (errout);
> int e1 = h->Register("Negative cluster energy", kMessageWarning);
> int e2 = h->Register("Cell number out of range : ", kMessageError);
> h->Suppress(kMessageDebug);
> TROOT->SetMessageHandler(h);
>
> ...
> TROOT->SendMessage("Entering cluster routine",kMessageDebug);
> { will print nothing, because kMessageDebug messages are suppressed }
> ...
> TROOT->SendMessage(e1);
> { will print : Error: Negative cluster energy }
> ...
> char buffer[200]; sprintf (buffer,"%d",num);
> TROOT->SendMessage(e2,buffer);
> { will print : Error: Cell number out of range : 100 }
> ...
> h->PrintStatistics();
> { will print : #of occurences Error
> 10 Negative cluster energy
> 2 Cell number out of range : }
>
> Of course this is only a first idea and the interface for the message
> handler should be defined for thorougly.
>
> Ciao
> Thomas
>
> ----------------------------------------------------------------------------
> Thomas Hadig, Ottensen, Donnerstr. 20, 22763 Hamburg (+49 40 39901186)
> office : I. Phys. Institut AAC, Room 1c354, Notkestr. 85, 22607 Hamburg
> hadig@rwth-aachen.de Tel. +49 40 8998 2312
> http://www-h1.desy.de/~hadig/ FAX +49 40 8998 4385
> ----------------------------------------------------------------------------
> The way to get rich with Object Orientied Programming --- Inheritance
> ----------------------------------------------------------------------------
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