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Smart Contracts Tips and Tricks

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📝 This article offers insights into Smart Contracts with helpful tips and tricks. If you have suggestions or questions, feel free to open an issue. We also welcome contributions through PRs.

Calling Smart Contracts Methods with Parameter Overloading​

Overview of Function Overloading​

Parameter overloading enables smart contracts to define multiple functions bearing the same name, differentiated only by their parameters. While this enhances legibility and organization, it complicates calls due to the need for precise method identification.

Example Code​

Below is a demonstration of invoking two versions of the funcWithParamsOverloading function in a smart contract, differentiated by their parameter types: uint256 versus address.

The Solidity code:

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.8.20 <0.9.0;


contract TestOverlading {

    function funcWithParamsOverloading(uint256 userId) public pure returns (string memory) {
        return  "called for the parameter with the type 'uint256'";
    }
    
    function funcWithParamsOverloading(address userAddress) public pure returns (string memory) {
        return  "called for the parameter with the type 'address'";
    }

}

The TypeScript:

import { Web3 } from 'web3';

const ABI = [
    {
        inputs: [
            {
                internalType: 'uint256',
                name: 'userId',
                type: 'uint256',
            },
        ],
        name: 'funcWithParamsOverloading',
        outputs: [
            {
                internalType: 'string',
                name: '',
                type: 'string',
            },
        ],
        stateMutability: 'pure',
        type: 'function',
    },
    {
        inputs: [
            {
                internalType: 'address',
                name: 'userAddress',
                type: 'address',
            },
        ],
        name: 'funcWithParamsOverloading',
        outputs: [
            {
                internalType: 'string',
                name: '',
                type: 'string',
            },
        ],
        stateMutability: 'pure',
        type: 'function',
    }
] as const;

(async function () {
  const web3 = new Web3(provider);

  const contract = new web3.eth.Contract(ABI, contractAddress);

  // Calling the function that accepts an address
  const res1 = await contract.methods['funcWithParamsOverloading(address)'](userAddress).call();

  // Calling the function that accepts a uint256
  const res2 = await contract.methods['funcWithParamsOverloading(uint256)'](userId).call();

})();

Handling Ambiguity in Overloaded Methods​

Omitting the explicit specification for overloading, as highlighted earlier, results in the default selection of the first method match in the ABI, along with a warning. Future web3.js releases will address this with an error to enforce stricter specification.

Demonstrating the Importance of Specificity​

To underline specificity's value, here's a scenario of invoking an overloaded function without specifying the parameter type:

// Assuming a contract with overloaded methods: funcWithParamsOverloading(uint256) and funcWithParamsOverloading(string)...

(async function () {
  try {
    // A call without specifying overloading results in a warning and choosing the first matched overload
    const ambiguousResult = await contract.methods.funcWithParamsOverloading('0x0123').call();
})();

This generates a console warning on the ambiguity and auto-selects the first matching function overload found in the ABI:

Multiple methods found that are compatible with the given inputs. Found 2 compatible methods: ["funcWithParamsOverloading(uint256) (signature: 0x...)", "funcWithParamsOverloading(string) (signature: 0x...)"] The first one will be used: funcWithParamsOverloading(uint256)

Future Considerations​

Future releases of web3.js, specifically version 5.x, will replace the warning with an error whenever multiple methods match a call without explicit overloading. This aims to foster greater precision in method invocation.

Key Takeaway for function overlading: Method Specification​

When working with overloaded smart contract methods, it's imperative to specify the intended method by appending its parameter types within parentheses, such as funcWithParamsOverloading(address) versus funcWithParamsOverloading(uint256). This ensures the accuracy of method invocation, leading to more efficient and clearer contract interactions.