errors.go

// User code:

// "Extract" still has return type "os.GetHeader, err"
c, err := containers.Get(client, "foo").Extract()

if err != nil {
  if gophercloud.HasErrorCode(err, gophercloud.ErrNotFound) {
    // ...
  }

  switch gophercloud.ErrorCode(err) {
    case gophercloud.ErrNotFound:
    case containers.BadContainerName:
  }
}

// Here's a quick sketch of the utility methods in gophercloud:

// These are *not* methods on BaseError, because then you'd have to either
// return _, gophercloud.BaseError from everything, or make the user cast
// all the time.

func ErrorCode(err error) CodeType {
  if casted, ok := err.(BaseError); ok {
    return casted.Code;
  }
  return nil;
}

func HasErrorCode(err error, code CodeType) bool {
  return ErrorCode(err) == code;
}