• References
  1. Openzeppelin: Proxy Patterns

Storage

• how to ensure that the logic contract does not overwrite state variables that are used in the proxy for upgradeability

1. Inherited Storage
2. Eternal Storage
3. Unstructured Storage
   1. fixed storage slots and constant state variables do not occupy storage slots. Instead, they’re embedded directly into the compiled contract bytecode.
   2. github test code

Proxy patterns (openzeppelin)

• background

advantage: immutable

disadvantage: cannot change the source code

• Key concepts

  fallback: to redirect calls to other contract implementations.

  delegatecall: CRUD in Proxy Contract.

• Transparent Proxy

  Proxy has upgrades.

  1 proxy 1 logic

  with role-based access

  proxy selector clashing

• UUPS(ERC-1822)

  https://medium.com/@pearliboy1/how-to-implement-an-upgradeable-smart-contract-with-uups-242c57f671ee

  Logic has upgrades.

  1 proxy 1 logic

  less expensive

• Beacon

  https://www.rareskills.io/post/beacon-proxy

  Beacon has upgrades.

  1 proxy 1 beacon

How can a proxy contract with the previous state be updated? new proxy contract casting a new implementation.atAddress(existing proxy contract address casting an implementation).