CallbackHandler

Abstract contract · src/core/utils/CallbackHandler.sol

Explained in: The DAO contract

Author: Aragon X - 2022-2023

This contract handles callbacks by registering a magic number together with the callback function's selector. It provides the _handleCallback function that inheriting contracts have to call inside their fallback() function (_handleCallback(msg.callbackSelector, msg.data)). This allows to adaptively register ERC standards (e.g., ERC-721, ERC-1115, or future versions of ERC-165) and returning the required magic numbers for the associated callback functions for the inheriting contract so that it doesn't need to be upgraded.

Dev: This callback handling functionality is intended to be used by executor contracts (i.e., DAO.sol).

security-contact: sirt@aragon.org

Events

CallbackReceived

event CallbackReceived(address sender, bytes4 indexed sig, bytes data)

Emitted when _handleCallback is called.

Parameter	Type	Description
sender	address	Who called the callback.
sig	bytes4	The function signature.
data	bytes	The calldata.

Errors

UnknownCallback

error UnknownCallback(bytes4 callbackSelector, bytes4 magicNumber)

Thrown if the callback function is not registered.

Parameter	Type	Description
callbackSelector	bytes4	The selector of the callback function.
magicNumber	bytes4	The magic number to be registered for the callback function selector.