SXS Currency Platform - 2023
Software design for a BRICS currency platform but also applicable to a set of State-based precious metal depositories running in parallel to the Federal Reserve. Many people expect a gold-backed digital currency from BRICS soon but I think the reality will be closer to this design.
An important part is the top-level pattern and design goals. This pattern is a set of financial realms (countries) executing point-to-point (P2P) transactions, which support multiple, asymmetrical exchange rates and impedance mismatches between realms.
A traditional class hierarchy needs 80-90% common behavior to work well. But this P2P + visitor is a composition pattern which supports much greater variation between countries and currencies.