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https://issues.apache.org/jira/browse/THRIFT-908?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Roger Meier resolved THRIFT-908.
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Resolution: Fixed
Assignee: Roger Meier (was: Christian Lavoie)
> Make required types actually required by the Haskell type system
> ----------------------------------------------------------------
>
> Key: THRIFT-908
> URL: https://issues.apache.org/jira/browse/THRIFT-908
> Project: Thrift
> Issue Type: Bug
> Components: Haskell - Compiler, Haskell - Library
> Affects Versions: 0.6
> Environment: ghc 6.12.3 on Mac OS X 10.6 (Haskell Platform 2010.2)
> Darwin -- 10.4.0 Darwin Kernel Version 10.4.0: Fri Apr 23 18:28:53 PDT 2010;
> root:xnu-1504.7.4~1/RELEASE_I386 i386
> The Glorious Glasgow Haskell Compilation System, version 6.12.3
> Reporter: Christian Lavoie
> Assignee: Roger Meier
> Attachments: v1-thrift-make-required-fields-required.patch
>
> Original Estimate: 6h
> Remaining Estimate: 6h
>
> Currently Haskell bindings consider all struct fields to be optional by
> having all struct fields be "Maybe $field". This patch removes that Maybe for
> required fields.
> THIS BREAKS EXISTING CODE.
> It's also probably incomplete -- I haven't looked too carefully yet at what
> happens on the server side if it tries to parse out an incomplete struct
> definition:
> {noformat}
> struct myStruct {
> 1: required byte foo,
> }
> {noformat}
> became after some code changes
> {noformat}
> struct myStruct {
> 1: optional byte foo,
> }
> {noformat}
> And code generated for the first version is asked to read a struct from the
> second version where foo is missing.
> I suspect after this patch the Haskell server commits hara-kiri trying to
> evaluate {{undefined}} _outside_ of the thrift generated code (so the client
> could would receive an error for something that the thrift generated code
> should have noticed as wrong). This is clearly inadequate.
> Consider this bug a thought experiment / request for comments until I
> validate that the patch is complete. It will still break existing code.
> First and foremost:
> # Thoughts?
> # What would be an acceptable way to handle the case described above for
> other Haskell users? Break the current interface some more by returning some
> error type (Either $struct $errMessags?). Throw a Haskell exception?
> # How do the other bindings handle parsing invalid data off the network?
> # The generator and generated code is fairly painful to read. Would the
> powers that be welcome a cleanup patch that moves as much of the
> t_hs_generator.cpp code to a boost::format-style system that uses template
> strings that look like Haskell code, and reformats the output to be indented,
> proper style Haskell code as much as possible?
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