com between contracts

pragma solidity ^0.4.22;
// Florian CASTELAIN <[email protected]> 10/02/2018

// Only signatures of the already deployed contract
// The equivalent of the ABI when using web3
// This is an abstract contract used to generate the needed ABI. The EVM does it itself
// --- WE REQUIRE THIS ONLY IF WE WANT TO INCLUDE PRECALCULATED ABI ---
contract target {
   function setValue(string v) public;
}


contract executer {
    
    target public tc;
    address public ta;
    
    // - USE THIS WITH PRECALCULATED ABI --
    function exeWithAbi(string value) public {
        tc.setValue(value);
    }
    
    function setAddress(address a) public {
        //Create instance of the target contract with it's address
        tc = target(a);
        ta = a;
    }
    
    // This is if we don't have the ABI.
    // keccak256 allows to create the function signature
    // WARNING: Here we use the address and not the sig of the contract
    //-- USE THIS WITHOUT PRECALCULTED ABI / THE ABSTRACT ON TOP IS NOT REQUIRED --
    function exeWithoutAbi(string v) public {
        require(ta.call(bytes4(keccak256("setValue(string)")),abi.encode(v)));
    }

}