In your project directory, run foundry init. This will create a boilerplate project.
Fund Your Account
You need to pay gas on the network to deploy the contract. Get testnet FTM through the faucet.
Create the Hello World Contract
In the initialized Foundry project in src/, create HelloWorld.sol:
// SPDX-License-Identifier: None
// Specifies the version of Solidity, using semantic versioning.
// Learn more: https://solidity.readthedocs.io/en/v0.5.10/layout-of-source-files.html#pragma
pragma solidity >=0.8.9;
// Defines a contract named `HelloWorld`.
// A contract is a collection of functions and data (its state). Once deployed, a contract resides at a specific address on the Fantom blockchain. Learn more: https://solidity.readthedocs.io/en/v0.5.10/structure-of-a-contract.html
contract HelloWorld {
//Emitted when update function is called
//Smart contract events are a way for your contract to communicate that something happened on the blockchain to your app front-end, which can be 'listening' for certain events and take action when they happen.
event UpdatedMessages(string oldStr, string newStr);
// Declares a state variable `message` of type `string`.
// State variables are variables whose values are permanently stored in contract storage. The keyword `public` makes variables accessible from outside a contract and creates a function that other contracts or clients can call to access the value.
string public message;
// Similar to many class-based object-oriented languages, a constructor is a special function that is only executed upon contract creation.
// Constructors are used to initialize the contract's data. Learn more:https://solidity.readthedocs.io/en/v0.5.10/contracts.html#constructors
constructor(string memory initMessage) {
// Accepts a string argument `initMessage` and sets the value into the contract's `message` storage variable).
message = initMessage;
}
// A public function that accepts a string argument and updates the `message` storage variable.
function update(string memory newMessage) public {
string memory oldMsg = message;
message = newMessage;
emit UpdatedMessages(oldMsg, newMessage);
}
}
Deploy the Contract
At this point, you are ready to deploy your contract:
You have your own node on the Opera testnet through which you will deploy the contract.
You have Foundry that you will use to deploy the contract.
You have a funded account that will deploy the contract.
