[jira] [Commented] (THRIFT-4060) Thrift printTo ostream overload mechanism breaks down when types are nested

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/THRIFT-4060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15848469#comment-15848469 ] 

ASF GitHub Bot commented on THRIFT-4060:
----------------------------------------

Github user jeking3 commented on the issue:

    https://github.com/apache/thrift/pull/1172
  
    So job #2 failed strangely in c_glib which is unrelated to this change.
    I pushed an empty change to kick a rebuild.  I expect it to clear...
    Here's the job that failed:
    https://travis-ci.org/apache/thrift/jobs/197100291


> Thrift printTo ostream overload mechanism breaks down when types are nested
> ---------------------------------------------------------------------------
>
>                 Key: THRIFT-4060
>                 URL: https://issues.apache.org/jira/browse/THRIFT-4060
>             Project: Thrift
>          Issue Type: Bug
>          Components: C++ - Compiler
>    Affects Versions: 0.9.3, 0.10.0
>         Environment: Ubuntu 14.04 LTS
>            Reporter: James E. King, III
>            Assignee: James E. King, III
>
> I'm in the middle of converting a project that provides some ostream operators (for logging purposes) for a number of thrift structures.  The project was using 0.8.0 and in 0.9.3 some ostream operator overloads were added with THRIFT-3336.  The solution that was provided here runs into complications if a thrift structure is contained within another one.  Take this simple example:
> h4. Thrift
> {noformat}
> namespace cpp example.detail
> struct Lower {
>    1: binary lowerBinary
> }
> struct Higher {
>     1: set<Lower> lowers
> }
> {noformat}
> h4. C++
> {noformat}
> namespace example {
> class Lower : public detail::Lower
> {
>     virtual void printTo(std::ostream& os) const override;
> }
> class Higher : public detail::Higher
> {
>     virtual void printTo(std::ostream& os) const override
>     {
>         os << lowers;   // WHOOPS!
>             // I cannot say os << lowers, since lowers is an example::detail concept
>             // it will print the thrift operator output here
>     }
> }
> }
> {noformat}
> I'm considering adding an anotation to the thrift IDL that the compiler will recognize that allows someone to say, "I am going to provide my own operator<< for this structure, don't generate one".
> This will allow existing projects with this issue to maintain compatibility without major refactoring.  Here is an example:
> {noformat}
> namespace cpp example.detail
> struct Lower {
>    1: binary lowerBinary
> } (cpp.customostream)
> struct Higher {
>     1: set<Lower> lowers
> }
> {noformat}
> For Lower, this would omit any operator << by the compiler, and thus also would not emit a printTo override for Lower.  It would be up to the implementation building against the generated code to provide an operator <<.



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