Journal

15 Nov 2021

• TIL
  • Solidity
  • EOSIO
• General

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TIL

I spent this morning’s deep work session studying more Solidity.

Solidity

Today’s session was pretty difficult. I’m at the point where things start to move faster and are harder to grasp. It’s where I think most beginners give up.

If it’s easy, you’re not learning.

• get the smart contract we are developing funded (nothing is free y’all)
• import an external npm package (chainlink) to use their smart contract(s)
  • convert ether to USD using chainlink data feed
  • we need a data feed because blockchain can’t use API calls (oracle problem)
• we need to pay the smart contract that is offering us the price feed service (once again, nothing is free)
  • find the address for the network and currency pair
  • Rinkeby: ETH -> USD
• decimals don’t work in solidity
  • not every machine used by every miner is guaranteed to implement the same floating-point standard
  • math is done entirely using fixed-point arithmetic

Here’s what I have so far; it’s unfinished code because there was too much to take in at too quick of a pace. I needed to stop and process before moving forward:

// SPDX-License-Identifier: MIT 

solidity >=0.6.6 <0.9.0;

import "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";

contract FundMe {
    
    mapping(address => uint256) public addressToAmountFunded;
    
    function fund() public payable {
        addressToAmountFunded[msg.sender] += msg.value;
        // ETH -> USD conversion rate
    }
    
    function getVersion() public view returns (uint256) {
        AggregatorV3Interface priceFeed = AggregatorV3Interface(0x8A753747A1Fa494EC906cE90E9f37563A8AF630e);
        return priceFeed.version();
    }
    
    function getPrice() public view returns(uint256) {
        AggregatorV3Interface priceFeed = AggregatorV3Interface(0x8A753747A1Fa494EC906cE90E9f37563A8AF630e);
        (,int256 answer,,,) = priceFeed.latestRoundData();
        return uint256(answer * 10000000000); // return in Wei
    }
}

EOSIO

I learned a bit about the EOSIO blockchain platform over the weekend.

• using delegated proof of stake
  • 21 block producers with 32 on standby
• apparently the most performant?
  • The resource I used for my learning was straight from EOSIO so they’re probably biased
• you can upgrade your smart contract?!
  • I’m doing a non-technical course so they don’t go into detail on how this is possible
  • investigation for another time
• no transaction cost!
  • I’m guessing the block producers get all their money from block rewards but besides the original 21, what’s the incentive for everyone else running in the network? 🤔
  • also investigation for another time

My certificate.

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General

I’ve been allocating too much time on learning Blockchain that I’ve fallen a bit behind on work. Everything requires such a delicate balance. I don’t do balance though. I’ll just go all-in on work momentarily and crank out a bunch of items. Then I can go back to all-in on blockchain studies!

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