ERC20 Smart Contract¶
The first smart contract is the Token. We don't invent it ourselves, we take the ERC20 Smart Contract from OpenZeppelin. In this version open-zeppelin v3, with Solidity 0.6 smart contracts:
Installation¶
In the console type:
npm install --save @openzeppelin/contracts@v3.0.0
Update from the Video
Note we will be using the v3.0.0 of openzeppelin contracts, instead of v3.0.0-beta.0
Possible Scenario¶
Let's think about a possible work-scenario. We will create a Token which let's you redeem a coffee at your favorite Coffee Store: StarDucks Coffee from Duckburg. It will look slightly different from other ERC20 tokens, since a coffee is hardly divisible, but still transferrable. Let's create our Token.
Adding the Token¶
Add a "MyToken.sol" file to the "/contracts" folder:
pragma solidity >=0.6.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract MyToken is ERC20 {
constructor(uint256 initialSupply) ERC20("StarDucks Capu-Token", "SCT") public {
_mint(msg.sender, initialSupply);
_setupDecimals(0);
}
}
Note
The ERC20Detailed has been deprecated and combined into the ERC20
contract default. The new ERC20 contract has a constructor with
arguments for the name and symbol of the token. It has a name "StarDucks
Capu-Token", a symbol "SCT". The new ERC20 contract has a default
decimal points of 18, we can change it to decimal points of 0 in the
constructor by calling the setupDecimals(uint8 decimals) function in
the ERC20 contract, with 0 as the argument.