## Welcome! ###### Snacks & drinks are available, please help yourself!  Join our slack group! <small> * Wifi: "Blockchain Meetup", Password: "<span>learnblockchain<!-- .element: class="fragment highlight-red" data-fragment-index="2" --></span>"<span style="font-size: 40px">←←←<!-- .element: class="fragment" data-fragment-index="2" --></span> * Code of Conduct: https://gitlab.com/TrevorJTClarke/blockchain-pdx/blob/master/Code_Of_Conduct.md </small> <small>Thank you to our sponsors: [Amberdata.io](https://amberdata.io), [Consensys](https://www.buidlnetwork.net/), [10net](10net.net)</small> --- ## Tonight's Happenings * Snacks & networking (How was it?) * Show & Tell (Amberdata, Gather) * BUIDL * Questions & Answers --- ## Show & Tell --- ### Shameless plug 🔌 ##### Amberdata.io <small> 1. A blockchain & market data API 2. Dashboards for blockchain 3. Fun things like a Slackbot 4. Try it free & show me what you build! </small> --- # ERC20 Token <!-- Put the link to this slide here so people can follow --> Follow along → https://hackmd.io/@1XqK8hlWRW6FMt8Q5EAXJw/erc20#/ <!-- .slide: data-transition="fade-out" --> --- <!-- .slide: data-transition="fade-in convex-out" --> ## Tools - Remix IDE - Brain 🧠 ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Goals - Introduce (*briefly*) the concept of ERC20 tokens & cryptoeconomics - Build & deploy ERC20 token ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Modus Operandi - Ask lot's of questions, that's why we're here! - Jot them down and ask at alloted interval - Send them in slack - lmgtfy.com/?q=your+question --- <!-- .slide: data-background="https://steemitimages.com/0x0/https://res.cloudinary.com/hpiynhbhq/image/upload/v1521625944/tuecbnfjrmpnzmxrglnk.gif" --> ## FIRE HOSE --- <!-- .slide: data-transition="convex-out" --> ## Cryptoeconomics > Cryptoeconomic approaches combine cryptography and economics to create robust decentralized P2P networks that thrive over time despite adversaries attempting to disrupt the network. > -- Nick Tomaino ---- <!-- .slide: data-transition="fade-in convex-out" --> ### Example: Bitcoin - transacting value (economy) - secured via hashing (cryptography) - distributed nodes (peer-to-peer / decentralization) ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Token economics > describes the study, design, and implementation of economic systems built on blockchain technology ---- <!-- .slide: data-transition="fade-in convex-out" --> ### Example ###### Chainlink (LINK) → wb3.io/LINK - utility token that provides access to the chainlink ecosystem ---- <!-- .slide: data-transition="fade-in" -->  ----  ---- ### Common Goal ###### To create incentives for stakeholders to participate ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ## What's an ERC20 Token? ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Inception Fabian Vogelsteller aka frozeman  ---- <!-- .slide: data-transition="fade-in convex-out" --> ## Adoption In September of 2017, EIP-20, formally adopted for Ethereum and defines a **standard interface*** for tokens. <small>*this will come up again </small> ---- <!-- .slide: data-transition="fade-in convex-out" --> ### Fun fact 🤓 Original method name proposals: createCheque, cashCheque, transferCheque tearCheque for unapprove --- <!-- .slide: data-transition="fade-in convex-out" --> <h2>EIP</h2> &nbsp; <small>(Ethereum Improvement Proposals)</small> "...a design document providing information to the Ethereum community, or describing a new feature for Ethereum or its processes or environment." <small>Source: [EIP 1](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1.md#what-is-an-eip)</small> <small> Similar to.. PEP (Python Enhancement Proposal) BIP (Bitcoin Improvemnt Proposal) </small> ---- <!-- .slide: data-transition="fade-in convex-out" --> ## ERC or EIP ?? <span> <!-- .element: class="fragment fade-out" data-fragment-index="2" --></span> <p>EIP - Ethereum Core/Network Improvements <!-- .element: class="fragment shrink" data-fragment-index="2" --></p> <p>ERC - Ethereum Contract Standards <!-- .element: class="fragment grow" data-fragment-index="2" --></p> ---- <!-- .slide: data-transition="fade-in convex-out" --> #### Note: ERC (*Ethereum Request for Comment*) <small>Just like RFC for web standards</small> --- <!-- .slide: data-transition="fade-in convex-out" --> ## So an ERC-20 is... #### The standard token interface ---- <!-- .slide: data-transition="fade-in convex-out" --> #### Defintion <p style="font-size: 10px"> eips.ethereum.org/EIPS/eip-20 </p>  --- <!-- .slide: data-transition="fade-in convex-out" --> ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- <!-- .slide: data-transition="fade-in convex-out" --> ## Time to buidl! ---- <!-- .slide: data-transition="fade-in convex-out" --> ### Steps <span>Contract Setup <!-- .element: class="fragment" data-fragment-index="1" --></span> <span>Transfer <!-- .element: class="fragment" data-fragment-index="2" --></span> <span>Approval <!-- .element: class="fragment" data-fragment-index="3" --></span> <span>Transfer From<!-- .element: class="fragment" data-fragment-index="4" --></span> <span>Events (Logs) <!-- .element: class="fragment" data-fragment-index="5" --></span> <span>Interfaces <!-- .element: class="fragment" data-fragment-index="6" --></span> ---- <!-- .slide: data-transition="fade-in convex-out" --> # [EIP20](https://eips.ethereum.org/EIPS/eip-20) --- ### Contract Setup Tasks: - Declare the pragma & contract - Declare state variables - Implement constructor ---- <!-- .slide: data-transition="fade-in convex-out" --> ## To [Remix](https://remix.ethereum.org/)! --- <!-- .slide: data-transition="fade-in convex-out" --> ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ### Transfer ###### Setup the ablility to transfer tokens between addresses Task: - Implement `transfer` & `balanceOf` methods ---- ###### Function Modifiers > Modifiers can be used to easily change the behaviour of functions. Modifiers are inheritable properties of contracts and may be overridden by derived contracts. > &mdash; Solidity Docs ---- ### the code ``` function transfer(address _to, uint256 _value) public returns (bool success) { // prevent overspending // update balances return } ``` ---- ## Back to Remix... --- <!-- .slide: data-transition="fade-in convex-out" --> ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ### Approve ###### Allow for other addresses to spend tokens on the behalf of another address. Task: - Implement `approve` & `allowance` methods ---- ## Back to Remix... --- ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ### Transfer From Task: - Implement `transferFrom` method ---- ### the code ``` function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) { // get allowance // require that value be < balances and allowance // update balances // check that allowance < MAX_UINT256 // deduct from allowance return } ``` ---- ## Back to Remix... --- ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ### Events Task: - Define and emit `Approval` & `Transfer` events ---- ## Back to Remix... --- ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ### Interface Task: - Define the interface ---- ## Back to Remix... --- ## Questions? <!-- .slide: data-background="https://media.giphy.com/media/XHVmD4RyXgSjd8aUMb/giphy.gif" --> --- ## Conculsion --- # Resources * [Meetup Archive Repository](https://gitlab.com/TrevorJTClarke/blockchain-pdx) * [Gitlab Slides](https://hackmd.io/@trevor/buidldapp-part2#/) * [Circles - dApp](https://github.com/TrevorJTClarke/Circles) * [Remix IDE](https://remix.ethereum.org) * [Amberdata API](https://docs.amberdata.io/)