dsa-connectors/docs/how-to-add-new-connector.md

How to add a new connector

You can create a new PR to add a new connector. To get the PR merged, certain requirements needs to be met which will be explained here.

New connector should follow the current directory structure

Common files for all connectors are in contracts/common directory.

• math.sol has methods for mathematical operations (DSMath)
• interfaces.sol contains the common interfaces
  • TokenInterface for ERC-20 interface including WETH
• stores.sol contains the global constants as well as methods getId & setId (Stores)
• basic.sol inherits DSMath & Stores contracts. This contains few details explained below
  • Wrapping & unwrapping ETH (convertEthToWeth & convertWethToEth)
  • Getting token & ETH balance of DSA

Connectors are under contracts/connectors directory, and should be formatted as follows:

• Connector events should be in a separate contract: events.sol
• Interfaces should be defined in a seperate file: interface.sol
• If the connector has helper methods & constants (including interface instances), this should be defined in a separate file: helpers.sol
  • Helpers contract should inherit Basic contract from common directory
  • If the connector doesn't have any helper methods, the main contract should inherit Basic contract
• The main logic of the contract should be under main.sol, and the contract should inherit Helpers (if exists, otherwise Basic) & Events

Few things to consider while writing the connector:

• Connector should have a public string declared name, which will be the name of the connector. This will be versioned. Ex: Compound-v1
• User interacting methods (external methods) will not be emitting events, rather the methods will be returning 2 variables:
  • _eventName of string type: This will be the event signture defined in the Events contract. Ex: LogDeposit(address,address,uint256,uint256,uint256)
  • _eventParam of bytes type: This will be the abi encoded event parameters
• The contracts should not have selfdestruct()
• The contracts should not have delegatecall()
• Use uint(-1) for maximum amount everywhere
• Use ethAddr (declared in Stores) to denote Ethereum (non-ERC20)
• Use address(this) instead of msg.sender for fetching balance on-chain, etc
• Only approve() limited amount while giving ERC20 allowance, which strictly needs to be 0 by the end of the spell.
• Use getUint() (declared in Stores) for getting value that saved from previous spell
• Use setUint() (declared in Stores) for setting value to save for the future spell

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