Interact between smart contracts does NOT work - ethereum

Question

I deployed two contracts, one is Callee and the other is Caller. Caller consumes functions provided by Callee. Function call directly to Callee is success, however, Caller does NOT work. Actually, I'v tried different cases from internet, none of them works. Do I miss some tricky things? Below is source code:
Callee.sol
pragma solidity ^0.4.6;
contract Callee {
uint[] public values;
function getValue(uint initial) public pure returns(uint) {
return initial + 150;
}
function storeValue(uint value) public {
values.push(value);
}
function getValues() public view returns(uint) {
return values.length;
}
}
Caller.sol
pragma solidity ^0.4.6;
contract Caller {
function someAction(address addr) public returns(uint) {
Callee c = Callee(addr);
return c.getValue(100);
}
function storeAction(address addr) public returns(uint) {
Callee c = Callee(addr);
c.storeValue(100);
return c.getValues();
}
function someUnsafeAction(address addr) public returns(bool){
return addr.call(bytes4(keccak256("storeValue(uint256)")), 100);
}
}
contract Callee {
function getValue(uint initialValue) public returns(uint);
function storeValue(uint value) public;
function getValues() public returns(uint);
}

Answer 1

Caller is technically working, but not doing what you're expecting.
The problem is that Caller.someAction is not marked with the pure or view modifiers, so your function call is triggering a new transaction. Transaction calls can't return values (it compiles and runs, but nothing is returned).
If you change Caller.someAction to be a pure function (and, also change Callee.getValue in the interface to be pure as well to match the contract), you will get the expected 250 returned.
pragma solidity ^0.4.6;
contract Caller {
function someAction(address addr) public pure returns(uint) {
Callee c = Callee(addr);
return c.getValue(100);
}
function storeAction(address addr) public returns(uint) {
Callee c = Callee(addr);
c.storeValue(100);
return c.getValues();
}
function someUnsafeAction(address addr) public returns(bool){
return addr.call(bytes4(keccak256("storeValue(uint256)")), 100);
}
}
contract Callee {
function getValue(uint initialValue) public pure returns(uint);
function storeValue(uint value) public;
function getValues() public returns(uint);
}
In terminal:
$ truffle migrate --reset
Compiling .\contracts\Callee.sol...
Compiling .\contracts\SimpleContract.sol...
Writing artifacts to .\build\contracts
Using network 'development'.
Running migration: 1_initial_migration.js
Replacing Migrations...
... 0x58a14c93acc733bb08e4bb56978d0bb466f8aca7659673426d989ee7e0e626f3
Migrations: 0x69ed5e4d6172639ed7d3c456ea8b2f2562c7dbcd
Saving successful migration to network...
... 0x9a3831076748cc6179ef3e4b3e466c3a4a871e196376bc22c984e91e95fdc567
Saving artifacts...
Running migration: 2_deploy_contracts.js
Replacing Caller...
... 0x7be6840c86a356decacc13967d50ef4fea30e86d30d69b19fb9998ce500c95e8
Caller: 0xb8c5e079af71813acac73bff9ca8e9e068660e86
Replacing Callee...
... 0xba7f588f9119e67968a7d6ab0110d79e1ecd3003e10cce3134018d42e966c8be
Callee: 0xd5c110c2f6566fd56749ec1a11328405f9935385
Saving successful migration to network...
... 0xc1526876e365189be1529a0943042e3a25e395a5cc19930ad907a694165104f1
Saving artifacts...
$ truffle console
truffle(development)> var caller = Caller.at('0xb8c5e079af71813acac73bff9ca8e9e068660e86');
undefined
truffle(development)> caller.someAction('0xd5c110c2f6566fd56749ec1a11328405f9935385');
{ [String: '250'] s: 1, e: 2, c: [ 250 ] }