Call functions of a contract deployed at a specific address from solidity

Question

I'm dealing with inheritance and external calls of contract from within solidity. I have deployed my data structure and filled it at an address MapAdr

My code can me schemed as follow. In my DataStructure.sol I have:

interface Graph {
function getNeighbours(uint8 id) external view returns (uint8[8]);
function getOrder() external view returns (uint8);
function isNeighbour(uint8 strFrom, uint8 strTo) external view returns 
(bool success);

}

contract DataStructure is Graph {
....code....
uint8 order;
constructor (uint8 size) {
order = size;
}
....code...
}

I deploy this contract and I save the address to MapAdr=0x1234567...

Now I go to my other contract

pragma solidity ^0.4.22;

import "./DataStructure.sol";


contract Data is Graph {
.....code....
DataStructure public data;

    constructor(address MapAdr) public {
    ....code...
    data = DataStructure(MapAdr);
    ....code...
    }
.....code....
}

But then DataStructure is deployed but it's address is not MapAdr.

There is a way to have an instance of the deployed contract at that specific MadAdr (so with that exactly data inserted in that datastructure) so I can query it's storage ?

The idea is to deploy several DataStructure contracts with different data inserted and then referiing to one specific when deploying Data contract.

Martin Zugnoni Martin Zugnoni · Accepted Answer · 2018-04-21T23:10:24

I'm not sure if this answers exactly your question, but I found this example very similar to what you are talking about, and I hope it can help you.

contract Admin {
  address private owner;

  function Admin() public { owner = msg.sender; }

  function getOwner() public returns (address) {
    return owner;
  }

  function transfer(address to) public {
    require(msg.sender == owner);
    owner = to;
  }
}

contract Lottery {
  string public result;

  Admin public admin = Admin(0x35d803f11e900fb6300946b525f0d08d1ffd4bed);  // Admin contract was deployed under this address

  function setResult(string _result) public {
    require(msg.sender == admin.getOwner());
    result = _result;
  }
}

As you can see, the Admin contract is deployed under the address 0x35d... and then it's used in the Lottery contract in the admin variable definition. Once you declare a variable as an instance of another contract, you can then use all the public interface of that contract. Check the admin.getOwner();execution.

Again, it's not following the same example as you mentioned, but it might be useful.

Hope it helps! ;-)

EDIT 1: Hardcoding the address of Admin instance in Lottery is probably a bad idea. This is just a very simple example. You might consider passing the Admin instance address as a parameter in the Lottery constructor instead. See comments below for more details.

Call functions of a contract deployed at a specific address from solidity

1 Answers