[boost] [filesystem][system] Usage guideline request

Subject: [boost] [filesystem][system] Usage guideline request
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2009-11-04 09:18:12

Hi,

I'm updating our software from Boost 1.33 to 1.40 and one of the major 
issues I encountered is using exceptions from Boost.Filesystem. The 
exception basic_filesystem_error has changed its interface in a breaking 
way, as it now relies on Boost.System error codes. I'm not aware of 
whether this change has been announced properly and the API deprecation 
period has been offered. And that is actually not what bothers me mostly.

The 1.33 version of Boost.Filesystem offered a number of unified error 
codes that our code used to react accordingly. For example, there were 
error codes out_of_space_error, already_exists_error, which were used on 
any platform supported by Boost.Filesystem. Now, with Boost.System in 
place, there are at least three sets of errors: system::errc, 
system::windows_error and system::linux_error, although, I assume, the 
latter is an addition to system::errc. In order to check for the older 
out_of_space_error I now have to write something like this:

   catch (basic_filesystem_error& e)
   {
     if (
       e.code() == system::errc::make_error_code(
         system::errc::no_space_on_device)
   #if defined(WIN32)
       || e.code() == system::windows_error::make_error_code(
         system::windows_error::disk_full)
   #endif
     )
     {
       // out_of_space_error
     }
   }

Is this the right way to do this? Is there a portable way to do it?

I tried to find a better way in the Boost.System documentation, but was 
highly disappointed as there is virtually no documentation at all. Also, 
no examples available for this library. I wonder how this library passed 
the review in the first place.