Re: [boost] [system] system-0.2 request for comments

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2006-07-24 09:34:06

Hi Beman

Beman Dawes <bdawes_at_[hidden]> wrote:
> * Class error_code now supports additional categories of
> errors, such as those that may bubble up from asio. I'll be
> watching for for a response from Chris to make sure this meets
> asio's needs.

Looks good! I have just uploaded a version of asio that has been
modified to use error_code and system_error where appropriate.
It's in the vault, in the System directory.

Just a few minor things:

- the system_error::what() function is defined in
  system_error.hpp without being inline, causing multiple
  definition linker errors.

- I'm not sure about the category names errno_ec and native_ec,
  since I keep reading the "ec" as error_code. I don't have any
  good suggestions, except perhaps more verbose names likes
  errno_category and native_error_category.

- The Jamfile is doing something strange when I try to link the
  boost_system library from the asio unit test Jamfile, but it
  works fine when used from non-test Jamfiles.

- The boost::identifier iostream operators aren't always working
  correctly with VC8. For example, try compiling the asio
  serialization example, which gives errors saying operator>>
  is ambiguous.

- error_code::new_category probably needs to be made
  thread-safe, or the limitations on when it can be called
  should be documented.

- You might want to add special handling when converting the
  success errno (i.e. 0) to a string on POSIX. The strerror
  function doesn't give you a string for it, so you end up with
  "EINVAL", which is a bit surprising.

Converting asio to use this stuff was a non-trivial exercise, so
I can confidently say I now have extensive experience using
these classes ;) I'm happy with the interface -- it's clean and
easy to use, particularly when it comes to defining new error
categories.

Cheers,
Chris