▫️Lesson 3.1: Contract Inheritance and Interfaces

Module 3: Advanced Smart Contract Development

Objective

This lesson focuses on strategies for optimizing gas usage in Ethereum smart contracts. Gas efficiency is crucial for minimizing the cost of deploying and interacting with contracts on the Ethereum network. By the end of this lesson, you will understand key optimization techniques and how to apply them to your smart contracts.

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Understanding Gas in Ethereum

Gas represents the computational effort required to execute operations on the Ethereum network. Every transaction, including smart contract deployment and function executions, requires gas. The cost of gas is paid in Ether (ETH), Ethereum's native cryptocurrency.

Why Optimize Gas?

• Cost Efficiency: Lower gas usage reduces the cost for users to interact with your contract.

• Network Efficiency: Efficient contracts contribute to less bloat on the Ethereum network, improving overall performance.

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Common Gas Optimization Techniques

1. Use Shorter Variable Types

   • Prefer uint256 and int256 for arithmetic operations, as they are the most gas-efficient types due to EVM optimizations.

   • For storage, use the smallest integer types that can accommodate your data (uint8, uint16, etc.) to pack variables tightly.

2. Minimize Storage Operations

   • Reading from and writing to storage are among the most expensive operations in terms of gas.

   • Optimize your contract by minimizing storage operations and using memory variables when possible.

3. Efficient Data Structures

   • Use mappings and arrays judiciously. Mappings are generally more gas-efficient than arrays for large datasets.

   • Consider using libraries like OpenZeppelin for standardized, gas-optimized data structures.

4. Loop Optimization

   • Loops can significantly increase gas costs, especially if they perform storage operations or have an unpredictable number of iterations.

   • Limit the use of loops where possible, and avoid state changes within loops.

5. Short-Circuiting in Conditionals

   • In logical operations, order conditions to take advantage of short-circuiting (e.g., place the most likely to fail or cheapest condition first).

6. Use External and View Functions Wisely

   • Mark functions as external if they are only called externally, as external functions can access arguments more cheaply than public functions.

   • Use view and pure function modifiers to indicate functions that don't modify state, which can save gas when called externally.

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Practical Example: Gas Optimization

Before Optimization:

pragma solidity ^0.8.0;

contract GasInefficient {
    uint[] public values;

    function addValue(uint value) public {
        values.push(value);
    }

    function computeSum() public view returns (uint sum) {
        for (uint i = 0; i < values.length; i++) {
            sum += values[i];
        }
    }
}

After Optimization:

pragma solidity ^0.8.0;

contract GasEfficient {
    uint public sum;
    uint public valuesCount;

    function addValue(uint value) public {
        sum += value;
        valuesCount++;
    }
}

Optimization Explanation:

• Removed the array and replaced it with a single sum variable to track the total, significantly reducing gas costs for both adding values and computing the sum.

• Introduced valuesCount to keep track of the number of values added, eliminating the need for a loop to compute the sum.

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Conclusion and Next Steps

Optimizing gas usage is essential for creating efficient and user-friendly smart contracts. By applying the techniques discussed in this lesson, you can reduce the gas costs associated with deploying and interacting with your contracts.