[Boost-users] exception, filesystem, system_error and consistency

Subject: [Boost-users] exception, filesystem, system_error and consistency
From: Michael Schuerig (michael.lists_at_[hidden])
Date: 2011-06-10 16:09:00

I haven't used C++ for several years and it's only a few weeks since 
I've looked at boost for the first time. Thus it's likely that my 
understanding of things isn't quite up to scratch.

In my first C++ project for years, I'm already using boost::filesystem 
and I'm using boost::system::system_error to wrap error codes returned 
by Linux API functions. For the latter purpose, I intend to use 
boost::exception for its ability to add diagnostic information to 
exceptions. At the top-level of my own code, I implement plain C 
interfaces and therefore need to convert all exceptions back to their 
original error codes.

Poring over docs and headers, I noticed that neither 
boost::system::system_error nor boost::filesystem::filesystem_error are 
derived from boost::exception. Instead they implement an independent 
exception hierarchy.

I found this disconcerting. For one thing, I have to catch and handle 
the respective exceptions separately. Far more importantly, though, I 
was expecting consistency among boost libraries and now see that this is 
not the case apparently.

When there is more than one way to do something, this automatically 
raises the question which one is the right way. Regarding boost, I'm 
wondering whether all libraries are created equal or whether there is an 
undocumented gradation from "stable, recommended" to "experimental, 
beware".

Michael

-- 
Michael Schuerig
mailto:michael_at_[hidden]
http://www.schuerig.de/michael/