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Dictionary

The Dictionary Contract is a crucial component of the UCS (ERC-7546) architecture. It manages the mapping of function selectors to their corresponding Function Contract addresses, acting as a dispatcher for the Proxy Contract.

Overview​

The Dictionary Contract in UCS maintains a dynamic mapping of function selectors to Function Contract addresses. This allows for function-level upgradeability and extensibility of the smart contract system.

Key Features​

  1. Function Mapping: Manages a mapping of function selectors to Function Contract addresses.
  2. Upgradeability: Allows for updating the implementation of existing functions.
  3. Extensibility: Supports adding new functions to the contract post-deployment.

Storage​

The Dictionary Contract maintains a mapping of function selectors to Function Contract addresses:

mapping(bytes4 => address) private implementations;

Events​

The Dictionary Contract emits an event when a function implementation is updated:

event ImplementationUpgraded(bytes4 functionSelector, address implementation);

Key Function​

getImplementation​

function getImplementation(bytes4 functionSelector) external view returns (address implementation)

Returns the Function Contract address for a given function selector.

Usage​

The Dictionary Contract is primarily used by the Proxy Contract to delegate calls. However, it can also be interacted with directly to manage the function mappings.

// Example usage
dictionary.setImplementation(FunctionA.functionA.selector, newFunctionAContractAddress);
dictionary.getImplementation(FunctionA.functionA.selector); // returns newFunctionAContractAddress

Security Considerations​

  1. Access control should be implemented to restrict who can update the function mappings.
  2. Care should be taken to ensure that the Function Contract addresses being set actually implement the expected function selectors.
  3. When updating function implementations, consider the potential impact on the overall system and existing state.

For more detailed information on security considerations, please refer to the Security Considerations document.