Access control

Solidity is a high-level programming language specially designed for writing smart contracts on the Ethereum blockchain. It is heavily influenced by the syntax of popular language

OpenZeppelin's Access Control Library:

OpenZeppelin's Access Control library is a powerful tool for managing authorizations and permissions in Ethereum smart contracts. It provides functionality to restrict access to certain parts of the contract only to specific users or predefined roles.

Example:

// contracts/MyContract.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";

contract MyContract is Ownable {
    function normalThing() public {
        // anyone can call this normalThing()
    }

    function specialThing() public onlyOwner {
        // only the owner can call specialThing()!
    }
}

Let's explain how it works

Importing the library

In the code above, the Access Control library is imported using the statement import "@openzeppelin/contracts/access/Ownable.sol";. This means that Access Control functionality is available in the MyContract contract.

Inheriting the Ownable class

The MyContract contract inherits from the Ownable class provided by the Access Control library. This means that MyContract will have access to the access control functionality provided by Ownable.

Using access control functions

In MyContract, you can see two functions: normalThing() and specialThing(). Let's see how they are affected by access control functions:

1. normalThing(): This function has no specific access restrictions. This means that anyone can call this function without any limitations.

2. specialThing(): This function is marked with the onlyOwner modifier, provided by the Ownable class. This modifier ensures that only the address that deploys the contract (the owner) can call this function. In this way, access to specialThing() is restricted to contract owners only.

Conclusion

OpenZeppelin's Access Control library provides a practical solution for managing permissions and roles in Ethereum contracts. By inheriting from the Ownable class and using the onlyOwner modifier, you can easily restrict access to certain parts of your contract to authorized users. This enhances security and enables you to implement effective governance features in your smart contracts.