Code-generating Away the Boilerplate in Our Migration Back to Spidermonkey``` We migrated from V8 back to SpiderMonkey due to differences in process models between our single-process MongoDB server and multi-process Chrome's tab-based architecture. We eliminated boilerplate by generating callbacks with unique template instantiations, implementing type integrations through policy-based class design, constrained method invocation with compile-time type lists, utilizing a Lippincott function for exception interchangeability, and metaprogramming away the boilerplate to create robust callbacks. To save boilerplate, we used per-callback template instantiations, added policy-based design, tidied up our interface, and created a wrapper that generates types from an appropriate policy. This resulted in 25 instances of WrapType and over 75 wrapped functions, with developers unfamiliar with this part of the codebase ramping up quickly and mimicking existing examples. The solution is almost identical to what we use today for production JavaScript integration.