Dynamically calling any other contract and function from contract

Question

This gives a contract the same ability to interact with other contracts (with its address as msg.sender), as an externally-owned account, right?

function call(address _contract, bytes calldata _calldata)
    external returns (bool, bytes memory)
{
    return _contract.call(_calldata);
}

Answer 1

To my understanding, Yes! Of course you have to do the abi.encodeWithSignature beforehand and add b as input as type address. You can also specify the amount of gas and the msg.value as shown in the code below.

Side note: When you call abi.encodeWithSignature the signature has to exactly match, e.g. uint instead of uint256 will lead to a failed call, although it is usually implied.

This contract for example enables you to call a function with one uint as input and specify the msg.value and gas:

pragma solidity "0.8.4";

contract externalcaller{
  function encodeforcall(string calldata signature, uint input)
    pure
    public
    returns(bytes memory)
  {
    return abi.encodeWithSignature(signature, input);
  }

  function call(string calldata signature, uint input, address b, 
                uint _gas, uint _weiamount)
    external
    payable
    returns
    (
      bool,
      bytes memory  
    )
  {
   bytes memory _calldata = encodeforcall(signature, input);
   (bool success, bytes memory data) = 
   b.call{gas: _gas, value: weiamount}(_calldata); 
   return (success, data);
  } 
}


contract callee{
  uint constant b = 1312;
  function getbplusa(uint256 a) public payable returns(uint){
    return b+a;
  }
}