This package contains the source code for Balancer V2 Weighted Pools, that is, Pools that swap tokens by enforcing a Constant Weighted Product invariant.
The pool currently in existence is WeightedPool (basic twenty token version).
There are subdirectories for common variants, which automatically updates some of their attributes to support more complex use cases. Examples are LiquidityBootstrappingPool for auction-like mechanisms, and ManagedPool for managed portfolios.
The lib directory contains internal and external common libraries, such as CircuitBreakerLib.
| Managed Pools are still undergoing development and may contain bugs and/or change significantly. |
|---|
Another useful contract is WeightedMath, which implements the low level calculations required for swaps, joins, exits and price calculations.
$ npm install @balancer-labs/v2-pool-weightedThis package can be used in multiple ways, including interacting with already deployed Pools, performing local testing, or even creating new Pool types that also use the Constant Weighted Product invariant.
To get the address of deployed contracts in both mainnet and various test networks, see balancer-deployments repository.
Sample Weighted Pool that computes weights dynamically on every swap, join and exit:
pragma solidity ^0.7.0;
import '@balancer-labs/v2-pool-weighted/contracts/BaseWeightedPool.sol';
contract DynamicWeightedPool is BaseWeightedPool {
uint256 private immutable _creationTime;
constructor() {
_creationTime = block.timestamp;
}
function _getNormalizedWeightsAndMaxWeightIndex() internal view override returns (uint256[] memory) {
uint256[] memory weights = new uint256[](2);
// Change weights from 50-50 to 30-70 one month after deployment
if (block.timestamp < (_creationTime + 1 month)) {
weights[0] = 0.5e18;
weights[1] = 0.5e18;
} else {
weights[0] = 0.3e18;
weights[1] = 0.7e18;
}
return (weights, 1);
}
...
}