[THRIFT-231] Ruby generated structs lack a hash method, and thus cannot be used as map keys or set members

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: Ruby - Compiler, Ruby - Library
• Patch Info: Patch Available
• Assignee: Bryan Duxbury
• Reporter: Bryan Duxbury
• Created: 11/Dec/08 21:56
• Updated: 01/Nov/11 02:52
• Resolved: 05/Jan/09 23:01

Description

Since generated structs don't define a hash method in Ruby, it defaults to a unique number every time. This means that even if two objects have equal values, they will not have equal hashcodes. As a result, if you try to create a set of these structs and subsequently attempt to test membership on an equal struct, it'll always return false. The same problem prevents structs from being used as map keys.

At the very least, we should define a hash method that always returns 0 and leave it up to the chaining to resolve the problem. A slightly more appropriate move would be to have the hashcode of a struct be the composition of its member values.