How to call contract function from other contract in Ethereum - ethereum

Question

I have a deployed contract "greeter" in Ethereum
contract mortal {
address owner;
function mortal() { owner = msg.sender; }
function kill() { if (msg.sender == owner) selfdestruct(owner); }
}
contract greeter is mortal {
string greeting;
function greeter(string _greeting) public {
greeting = _greeting;
}
function greet() constant returns (string) {
return greeting;
}
}
And I want to create another contract, which will call function "kill" from my first contract. The main idea is that this 2 contracts is different. I publish contract A and then publish contract B, which calls A.
How I can do that?
Something like this, but from contract...
var contract = web3.eth.contract(contractAddress, ABI);
contract.call().kill();

Answer 1

Approximately like this, but there's a catch.
pragma solidity ^0.4.6;
contract Mortal {
address owner;
function Mortal() { owner = msg.sender; }
function kill() { if (msg.sender == owner) selfdestruct(owner); }
}
contract Greeter is Mortal {
string greeting;
function Greeter(string _greeting) public {
greeting = _greeting;
}
function greet() constant returns (string) {
return greeting;
}
}
contract Killer {
function destroyVictim(address victim) {
Greeter g = Greeter(victim);
g.kill();
}
}
That's a basic syntax. The ABI gets picked up by including Greeter in the source file along with Killer; that is, the compiler can "see it".
So far, so good.
The issue that arises is that Greeter is going to ignore the command, owing to if(msg.sender==owner). It won't be. It will be whatever address Killer got.
A possible solution to this before Greeter is deployed is to anticipate the need for a changeOwner() function, usually reserved for only the current owner.
Hope it helps.