Custom Orders
Custom orders leverage the IConditionalOrder or IConditionalOrderGenerator interface to enable sophisticated trading strategies based on on-chain conditions. The framework recommends extending BaseConditionalOrder for most implementations, as it handles signature verification automatically.
Key Interfaces
- IConditionalOrder provides the foundational verification method
- IConditionalOrderGenerator extends this by adding order generation capabilities on-chain
The verify function checks discrete order validity, while getTradeableOrder produces executable orders for the CoW Protocol API.
BaseConditionalOrder Advantages
This abstract contract streamlines development by automating:
- Order hash verification
- ERC165 interface support
Developers focus solely on implementing the order generation logic through the getTradeableOrder function, which must return a valid GPv2Order.Data struct.
Implementation Examples
TradeAboveThreshold
Executes when an owner’s token balance exceeds a specified threshold, selling the entire balance.
PerpetualStableSwap
Automatically rebalances between two tokens based on relative holdings, applying a configurable spread.
Error Communication
Specialized revert errors guide watchtowers on retry behavior:
| Error | Behavior |
|---|
PollTryNextBlock | Temporary condition, retry soon |
PollTryAtBlock / PollTryAtEpoch | Order valid at specific time |
PollNever | Permanent invalidity, stop monitoring |
OrderNotValid | Generic failure condition |
Advanced Features
- Context-based cabinet storage for persistent values
offchainInput parameters for dynamic watchtower-provided data- Validity bucketing prevents hash collisions across sequential queries
Best Practices
- Maintain gas efficiency in
getTradeableOrder
- Ensure deterministic logic within validity buckets
- Employ clear error messaging
- Implement proper ERC165 interface support
Security Considerations
- Validate external calls
- Manage arithmetic carefully
- Address reentrancy risks
Last modified on March 4, 2026
