Suggestion: Replace Hashie::Mash with OpenStruct

Hashie has generally been noted as having lackluster performance, large memory overhead, and results in a few pitfalls. For instance, see https://www.schneems.com/2014/12/15/hashie-considered-harmful.html.

OpenStruct objects can provide much of the same benefits (e.g. attributes accessible by symbol or string keys, as well as method calls) with less overhead and easier understanding. I tried doing this myself, but some of the Slack client is partially dependent on some strange behavior around Hashie::Mash (particularly on recursive hashes within a Slack::Messages::Message) - this could all be changed, but I felt it was getting to be a larger effort that should have community buy-in before being done. As a result, I figured I would raise this suggestion here. Thanks!

Start by locating the Slack client’s Hashie::Mash usage, especially recursive hashes within Slack::Messages::Message, and compare the existing behavior with OpenStruct. The work is complete only when the replacement preserves the required message behavior and the project has tests covering the affected client responses.