[jira] [Commented] (THRIFT-2854) GO Struct writer and reader looses important error information

["Chi Vinh Le (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/THRIFT-2854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14223825#comment-14223825 ] 

Chi Vinh Le commented on THRIFT-2854:
-------------------------------------

Example of code that is currently being generated:
{code}
func (p *Bonk) ReadField1(iprot thrift.TProtocol) error {
  if v, err := iprot.ReadString(); err != nil {
    return fmt.Errorf("error reading field 1: %s", err)
  } else {
    p.Message = v
  }
  return nil
}
{code}


> GO Struct writer and reader looses important error information
> --------------------------------------------------------------
>
>                 Key: THRIFT-2854
>                 URL: https://issues.apache.org/jira/browse/THRIFT-2854
>             Project: Thrift
>          Issue Type: Bug
>          Components: Go - Compiler
>    Affects Versions: 0.9.2
>            Reporter: Chi Vinh Le
>             Fix For: 0.9.3
>
>
> The GO Compiler generates code for a struct so that the following occurs:
> When an error occurs while reading or writing, a new error is created with additional text information using {code}fmt.Errorf{code}.
> By doing this the original error is completely lost. This is a real problem because errors of type TTransportException and TProtocolExceptions which contain additional information are lost. This will cause bad error handling, as the server implementation is dependent on those information.
> In my personal fork, I have a quick'n dirty fix for this, but I'm looking for a better option.
> Maybe instead of {code}fmt.Errorf{code} we could use this:
> {code}
> // Prepends additional information to an error without losing the Thrift interface
> func PrependError(err error, prepend string) error {
>   if t, ok := err.(TTransportException); ok {
>     return NewTTransportException(t.TypeId(), prepend+t.Error())
>   }
>   if t, ok := err.(TProtocolException); ok {
>     return NewTProtocolExceptionWithType(t.TypeId(), errors.New(prepend+err.Error()))
>   }
>   if t, ok := err.(TApplicationException); ok {
>     return NewTApplicationException(t.TypeId(), prepend+t.Error())
>   }
>   return errors.New(prepend + err.Error())
> }
> {code}
> I want to discuss this first here, because making a patch is quiet some work and I don't want major changes after I create a fix.



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