Import value from other contract

Question

I am trying to pass configuration values from one contract to another, so I can change them and avoid transaction fees.

I have two contracts:

pragma solidity ^0.4.23;

import "./two.sol";

contract One{

    string name;

    constructor() public{

    }

    Two two;

    function getNameFromOtherContract() public returns(string) {
        name = two.getName();
        return name;
    }
}

And second:

pragma solidity ^0.4.23;

contract Two{

    constructor() public{
    }

    function getName() external pure returns (string name) {
        name = "Amel";
    }
}

When I triger getNameFromOtherContract I get:

transact to One.getNameFromOtherContract errored: VM error: revert. revert The transaction has been reverted to the initial state.

What would be the correct syntax and solution for this approach?

Answer 1

1) You're one contract is not setting the variable two to the deployed two contract's address. This is why you're getting a revert error.

Rev A) fixed code

pragma solidity ^0.4.23;

import "./Two.sol";

contract One{

    string name;
    Two two;

    constructor() public{
        two = new Two();
    }

    function getNameFromOtherContract() public returns(string) {
        name = two.getName();
        return name;
    }
}

Rev B (actually setting the address of contract two via the constructor of contract one. Note: this requires two to be deployed before one)

pragma solidity ^0.4.23;

import "./Two.sol";

contract One{

    string name;
    Two two;

    constructor(address _two) public{
        require(_two != address(0));
        two = Two(_two);
    }

    function getNameFromOtherContract() public returns(string) {
        name = two.getName();
        return name;
    }
}

2) I'm not sure how you're going to accomplish this part: change them and avoid transaction fees. Please explain further and I'll be happy to assist.