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https://issues.apache.org/jira/browse/THRIFT-5314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17288781#comment-17288781
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Allen George commented on THRIFT-5314:
--------------------------------------
I've taken a crack at this here: https://github.com/apache/thrift/pull/2337
After looking at the alternatives:
# the one I proposed:
https://issues.apache.org/jira/browse/THRIFT-5314?focusedCommentId=17235560&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-17235560)
# the flatbuffer implementation:
https://github.com/google/flatbuffers/pull/6098/files
I decided that comments from others were correct: the flatbuffer one was
cleaner, avoided the use of a magic {{__Unknown}} and still allowed us to use
basic matching.
At the core, we now implement enums using the newtype idiom:
Old way:
{noformat}
pub enum Foo {
VariantOne = 1,
VariantTwo = 2.
...
}
{noformat}
New way:
{noformat}
pub struct Foo(pub i32);
impl Foo {
pub const VARIANT_ONE: Foo = 1;
pub const VARIANT_TWO: Foo = 2;
pub const ENUM_VALUES: &'static [Self] = &[Self::VARIANT_1, Self::VARIANT_2];
...
}
{noformat}
I've also implemented {std::convert::From} for some types.
Please note that to conform to the Rust style guide enum variants are now in
uppercase as opposed to camelcase. Whenever possible I prefer to use Rust's
default conventions.
cc [~rdettai]
> Enum forward compatibility
> --------------------------
>
> Key: THRIFT-5314
> URL: https://issues.apache.org/jira/browse/THRIFT-5314
> Project: Thrift
> Issue Type: Bug
> Components: Rust - Compiler, Rust - Library
> Affects Versions: 0.13.0, 0.14.0
> Reporter: Remi Dettai
> Assignee: Allen George
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> It seems that enums in the Rust implem are not forward compatible. As Thrift
> enums are mapped 1:1 to Rust enum, if a newer Thrift definition adds a case
> to an enum, an error will be returned when parsing the message.
> Is this intended? Is there a workaround?
> (We met this problem in the Rust parquet implem:
> https://issues.apache.org/jira/browse/ARROW-10553)
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