[context] chainlink data feed integration

chainlink interface

interface AggregatorV3Interface {
  function decimals() external view returns (uint8);
 
  function description() external view returns (string memory);
 
  function version() external view returns (uint256);
 
  function getRoundData(
    uint80 _roundId
  ) external view returns (
    uint80 roundId,
    int256 answer,
    uint256 startedAt,
    uint256 updatedAt,
    uint80 answeredInRound
  );
 
  function latestRoundData() external view returns (
    uint80 roundId,
    int256 answer,
    uint256 startedAt,
    uint256 updatedAt,
    uint80 answeredInRound
  );
}

integration

pragma solidity ^0.8.0;
 
contract ChainlinkIntegrationSnippet {
  address public feed;
 
  constructor(address feed_) {
    feed = feed_;
  }
 
  function getPrice() external view returns (uint256) {
    // fetch price
    (
      /* uint80 roundId */,
      int256 answer,
      /* uint256 startedAt */,
      /* uint256 updatedAt */,
      /* uint80 answeredInRound */
    ) = AggregatorV3Interface(feed).latestRoundData();
 
    // safe cast
    return uint256(answer);
  }
}