Re: [Boost-users] [Test] Making use of boost::exception_diagnostic_information and friends

Subject: Re: [Boost-users] [Test] Making use of boost::exception_diagnostic_information and friends
From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2009-08-10 14:45:48

Emil Dotchevski <emildotchevski <at> gmail.com> writes:

 > Diagnostic_information is used when you catch an exception you know
 > nothing about which might contain any type and any number of data
 > useful for diagnostic purposes. How would the user format something
 > like this?

Every exception has a point of inception. This is the info I'd like to 
get my hands on. These can be reported in XML, human readable and any 
other format user may opt to implement.

 > >> Since the testing framework wouldn't know anything about the
 > >> exception
 > >> it's reporting, it should catch(...) and leave it up to
 > >> current_exception_diagnostic_information to provide all the
 > >> information it can dig out from whatever the current exception may 
 > >> be.
 > >
 > > 1. It will never get to the catch(...) execution monitor has tons 
of > > other catch
 > > clauses (including catch (std::exception)) which will trigger first.
 >
 > So you could do:
 >
 > catch( foo & e )
 > {
 >     //do other stuff, and then:
 >     std::cerr << boost::diagnostic_information(e);
 > }
 > catch( boost::exception & e )
 > {
 >     //do other stuff, then:
 >     std::cerr << boost::diagnostic_information(e);
 > }

1. Isn't supposed to be other way around: first catch boost::exception, 
followed
by catch foo? I'd prefer to have boost:exception related logic in a 
single catch
clause instead of being spread between 20.

2. I do not want to print anything. I collect information and return it (by
throwing another exception) to the higher level, which in turn decides 
how and
where to report it.

 > catch( std::exception & e )
 > {
 >     //do other stuff furst, then:
 >     std::cerr << boost::diagnostic_information(e);
 > }
 > catch( ... )
 > {
 >     std::cerr << boost::current_exception_diagnostic_information();
 > }

What is the point of trying to dig something here? Wouldn't the 
boost::exception based exception will always be caught in 'catch 
boost::exception' clause above?

 > > 2. execution monitor is very careful about memory being used. How
 > > about diagnostic_information?
 >
 > You'd have to define the meaning of 'careful' :) but if you're asking
 > how much memory diagnostic_information allocates, it simply composes a
 > std::string which it returns to the caller.

execution_monitor does not allocate memory at all in the point of error 
processing.

 > > 3. I pretty much only need file, line and function name. Are you
 > > saying I can't do what you are doing inside diagnostic information
 > > to get a hold of them?
 >
 > If the exception was thrown by BOOST_THROW_EXCEPTION, then yes you'd
 > have file, line and function name.

Ok. So how do I do this?

 > However, objects that derive from
 > boost::exception can have data of arbitrary type, some of it added at
 > the point of the throw, some of it added later (meaning, it depends on
 > the callers of the function that throws.)
 >
 > Do you not want to display all that information when you catch a user
 > exception in the testing framework?

I do not mind if method 'what' would generate "rich" error message 
including everything, but the information about the point of inception 
(Or some other method)

Gennadiy