Solidity: Pass a custom interface as argument in a function which changes

Question

I am writing a smart contract as follow:

contract MyContract {

   function doSomething(address newAddress, interface newInterface) {
       _newAddress = newInterface(newAddress);
       _newAddress.doSomething();
    }

}

I could define my interface beforehand. But I would like to pass every-time a new one because my newInterface could CHANGE overtime.

So I am looking a bit at the different alternatives, any idea? Thanks

Answer 1

interface is reserved for defining a set of functions on a predefined contract. You could add interface function you intend to add into the external contract in the future, but this is not recommended as you likely will change what you want later.

I suggest looking into external calls directly, here's one example of how this can be done:

bytes memory payload = abi.encodeWithSignature("mintFromGamify(uint256,address)", _amount, _to);
(bool success, bytes memory result) = governanceToken.call(payload);

To extend you contract to add functionality to calling external contracts your would do something similar to the following (KEEP this data private and ownerOnly permissions):

Create a variable for the byte code: mapping(uint256 -> bytes memory) byteCode;

Generate the byte code payload, which could be generated offline via the function listed above (this will have to be coded for each function but does not require the function to be hard-coded). Then add the external call data via:

function addByteCode(bytes memory input, uint256 index) public {
    require(byteCode[index] != 0, "memory not avalible here");
    byteCode[index] = input;
}

Now that you have a collection byte codes in memory just call the appropriate index:

function externalCaller(address targetContract, uint256 index) public 
    returns (bool){
    (bool success, bytes memory result) = targetContract.call(byteCode[index]);
}