Solidity - lesson 1 | HackIndia Skills

Solidity - lesson 1 | HackIndia Skills | HackIndia

Example

First contract

This example stores one project profile. It is like a mini on-chain record for a HackIndia submission. It has one owner, one public title, and a way to update the title.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.37;

contract ProjectProfile {
    address public immutable owner;
    string public title;

    error NotOwner(address caller);
    error EmptyTitle();

    event TitleUpdated(string oldTitle, string newTitle);

    constructor(string memory initialTitle) {
        if (bytes(initialTitle).length == 0) {
            revert EmptyTitle();
        }

        owner = msg.sender;
        title = initialTitle;
    }

    function updateTitle(string calldata newTitle) external {
        if (msg.sender != owner) {
            revert NotOwner(msg.sender);
        }

        if (bytes(newTitle).length == 0) {
            revert EmptyTitle();
        }

        string memory oldTitle = title;
        title = newTitle;

        emit TitleUpdated(oldTitle, newTitle);
    }
}

Write your first clean contract

One clean idea

What to include

First contract

Read the structure

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Avoid tutorial leftovers

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