[Coin-discuss] Message handling

[John J Forrest]

If COIN is to be taken seriously it needs uniform message handling.  I put
together a message handler for COIN LP which has just received IBM
clearance.  I have put this in Osi (the development branch) so people can
look at it and tell me to start again.

There is a simple message handler, from which user specific ones can be
derived.  For each module there is a simple description of the messages
e.g. Osi/include/OsiOsiMessage.hpp and OsiOsiMessage.cpp

So for instance - for the developer, OSI_MPS_DUPROW is defined in
Osi/include/OsiOsiMessage.hpp

and in OsiOsiMessage.cpp the text is given as:

 {OSI_MPS_DUPROW,3004,0,"Duplicate row %s at line %d < %s >"},

In the code the message is created by:

        handler_->message(OSI_MPS_DUPROW,messages_)
                <<mpsfile.rowName()<<mpsfile.cardNumber()<<mpsfile.card()
                <<OsiMessageEol;

and the default would print this to stdout as

Osi3004W Duplicate Row XYXYXY at line 1234 <    COLUMN7  XYXYXY
4.0>

A bit clumsy but fairly near to std::cout syntax.

The user (as against developer) can create a derived message handler - see
OsiOslSolverInterfaceTest.cpp for an example.
The amount of detail wanted may be specified etc.

Many design features are similar to OSL's EKK messages (which were designed
- so obviously I was not involved :-)).  This can be changed.

I like language support so that is in - if a particular message is not
there it defaults to US english  - see OsiMpsReaderTest.cpp for some
atrocious Italian.

In OsiOslSolverInterfaceTest.cpp I have put in code to allow OSL messages
to be passed to the message handler.  This can be used as a template for
anyone who has a sophisticated program calling OSL.

It is a bit sketchy for now and there are very few messages There are many
more messages in Clp.

Comments welcomed.

John Forrest