How to call parent constructor with parameters generated in the child contract

Question

I need to create a ERC721 contract where ERC721 constructor properties (name, symbol) are not provided directly but they are calculated from the new constructor parameters. I am trying like this but it does not work

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.2;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC721 {
    constructor(
        string someparameter
    )  {
        // transform "someparameter into two variables with string manipulation,
        // let's say "somparameterName" and "someparameterSymbol"
        ...
        super(somparameterName, someparameterSymbol)
    }
}

Is this possible? It seems like it only allows using ERC721(_name, _symbol) after constructor(string someparameter) and before the body of the constructor ({...})

Thanks

Answer 1

You could create a function that parses the input and call the constructor with the result

// SPDX-License-Identifier: MIT
pragma solidity >=0.4.0 <0.9.0;


contract A  {
    string public b;

    constructor(string memory a) {
        b = a;
    }
}

contract B is A {
    constructor(string memory x) A(foo(x)) {

    }

    function foo(string memory z) internal pure returns (string memory) {
        return string(abi.encodePacked(z, "polo"));
    }
}