🔙Gas Saving Technique 32: Optimal Use of Named Return Variables in Solidity

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Introduction: In Solidity, function return values can be explicitly named, creating named return variables. While they provide clarity, misuse can lead to redundant operations and increased gas costs. This tutorial will dive into the efficient use of named return variables for both code readability and gas optimization.

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Concept:

1. Named Return Variables: When defining functions in Solidity, it's possible to give names to return variables. This can enhance readability and reduce code redundancy.

2. Redundant Return Statements: If a function has named return variables and also includes an explicit return statement, it can result in both redundancy and extra gas costs.

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Examples & Recommendations:

Consider the code snippets from StakedCitadelLocker.sol:

1. Before Optimization:

   solidityCopy codefunction getRewards() external returns (uint256 userRewards) {
       // ... some logic that sets userRewards ...
       return userRewards;
   }

2. After Optimization:

   solidityCopy codefunction getRewards() external returns (uint256 userRewards) {
       // ... some logic that sets userRewards ...
   }

Note: When using named return variables, the value assigned to them gets automatically returned at the end of the function. Explicitly returning them is redundant.

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Step-by-Step Guide for Implementing the Named Return Variable Optimization:

1. Identification: Scan your contract for functions that define named return variables and also use an explicit return statement.

2. Removal: For each identified function, remove the explicit return statement. Ensure the logic correctly assigns the value to the named return variable, as it will be automatically returned.

3. Verification: Review each optimized function to confirm that the logic remains intact.

4. Testing: Thoroughly test the contract to ensure that functions still behave as expected and return the correct values.

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Benefits:

1. Gas Savings: Removing unnecessary return statements can save gas during contract deployment and execution.

2. Code Readability: By avoiding redundancy and utilizing named return variables, the code remains clean and intent-driven.

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Conclusion: The use of named return variables in Solidity can provide clarity and improved readability. However, care must be taken to avoid redundancies like unnecessary return statements, which can lead to gas inefficiencies. By efficiently using named return variables, developers can maintain clean code while also optimizing for gas savings.