Clone Smart Contracts with Ease: Factory Pattern in Solidity

Optimizing Smart Contract Deployment with the Factory Pattern

The High Cost of Deploying Smart Contracts

In blockchain development, deploying sets of data into a blockchain can be a costly process. Each new data deployment incurs fees, which can add up quickly. This is especially true when deploying smart contracts on blockchain, as each contract deployment requires gas fees. However, there is a way to optimize this process using the factory pattern.

Introducing the Factory Pattern

The factory pattern is a well-known programming pattern that allows you to create multiple instances of objects without directly creating them. In Solidity, a factory is a contract that deploys multiple instances of other contracts. This pattern is particularly useful when you need to create different types of objects at runtime.

Benefits of Using the Factory Pattern

The factory pattern offers several benefits, including:

• High gas-efficiency: Deploying multiple contracts with high gas-efficiency
• Contract tracking: Keeping track of all deployed contracts
• Gas savings: Saving gas on multiple contract deployments

When to Use the Factory Pattern

The factory pattern is effective in situations where:

• You need to quickly produce multiple instances of a smart contract at runtime
• You’re dealing with a large number of contracts that all have the same functionalities

Types of Factory Patterns

There are two common types of factory patterns in Solidity:

• Normal Factory Pattern: Deploys multiple instances of other contracts without optimization
• Cloned Factory Pattern: Deploys multiple instances of other contracts with optimization to save gas on each deployment

Creating a Simple Smart Contract

Let’s create a simple smart contract that will be used by the factory contract to deploy multiple instances of it:
“`
pragma solidity ^0.8.0;

contract Foundation {
address public owner;
uint public value;

constructor(address _owner, uint _value) {
    owner = _owner;
    value = _value;
}

}
“`
Creating a Factory Contract

Now, let’s create a factory contract that will create individual instances of the Foundation contract using the normal factory pattern:
“`
pragma solidity ^0.8.0;

import “./Foundation.sol”;

contract FoundationFactory {
address[] public _foundations;

function createFoundation(address _owner, uint _value) public {
    Foundation foundation = new Foundation(_owner, _value);
    _foundations.push(address(foundation));
}

function allFoundations() public view returns (address[] memory) {
    return _foundations;
}

}
“`
The Drawback of the Normal Factory Pattern

The normal factory pattern has a major drawback: high gas costs. Each time an instance of the Foundation contract is deployed, a gas fee of 32,000 Gwei is charged. This is where the cloned factory pattern comes in handy.

The Cloned Factory Pattern

The cloned factory pattern is a mechanism that deploys only one instance of the Foundation contract and has all other instances behave as proxies, delegating calls to the first instance of the Foundation contract. This allows each instance of the Foundation contract to have its own state and simply uses the instance of the Foundation contract established by us as a library.

Implementing the Clone Factory Contract

To implement the clone factory contract, you’ll need to install the clone-factory package and import the Ownable contract from the OpenZeppelin library:
“`
pragma solidity ^0.8.0;

import “./Foundation.sol”;
import “@openzeppelin/contracts/access/Ownable.sol”;

contract CloneFactory {
address public libraryAddress;

constructor(address _libraryAddress) {
    libraryAddress = _libraryAddress;
}

function createFoundation(address _owner, uint _value) public onlyOwner {
    address instance = address(new Foundation(_owner, _value));
    // delegate calls to the library contract
    //...
}

}
“`
Comparison between Normal and Clone Factory Patterns

To examine the difference in gas cost between the CloneFactory and the normal factory, we’ll deploy each contract to a testnet, execute each contract’s createFoundation function, and check the transaction hash in the explorer to know how much gas was used.

Conclusion

In this article, we’ve explored the factory pattern, its benefits, its types, and when it is best fitted for our smart contracts. We’ve also established that the cloned factory pattern is the right pattern for deploying multiple instances of our Solidity smart contract due to its gas cost efficiency.