與其他合約互動的最佳實踐

我想知道與其他契約互動的最佳方法和最佳實踐是什麼。

這裡是MyFriendToken.sol和MyService.sol：

MyFriendToken.sol 我想知道與其他契約互動的最佳方法和最佳實踐是什麼。

這裡是MyFriendToken.sol和MyService.sol：

MyFriendToken.sol

pragma solidity ^0.4.0;
contract ERC20 {
   //here are the same function in the TokenContractFragment
   //https://theethereum.wiki/w/index.php/ERC20_Token_Standard

   function allowance(address _owner, address _spender) constant returns (uint remaining);
   event Transfer(address indexed _from, address indexed _to, uint _value);
   event Approval(address indexed _owner, address indexed _spender, uint _value);


   function approve(address _spender, uint256 _amount) returns (bool success) {
       if ((_amount != 0) && (allowed[msg.sender][_spender] != 0)) {
           return false;
       }
       allowed[msg.sender][_spender] = _amount;
       Approval(msg.sender, _spender, _amount);
       return true;
   }

   function transfer(address _to, uint256 _amount) onlyPayloadSize(2 * 32) returns (bool success) {
       if (balances[msg.sender] >= _amount && _amount > 0 && balances[_to] + _amount > balances[_to]) {
           balances[msg.sender] -= _amount;
           balances[_to] += _amount;
           Transfer(msg.sender, _to, _amount);
           return true;
       } else {
           return false;
       }
   }

   function transferFrom(address _from, address _to, uint256 _amount)
   returns (bool success) {
       if (
       balances[_from] >= _amount
       && allowed[_from][msg.sender] >= _amount //the transfer is approved
       && _amount > 0
       && balances[_to] + _amount > balances[_to]) {
           balances[_from] -= _amount;
           allowed[_from][msg.sender] -= _amount;
           balances[_to] += _amount;
           Transfer(_from, _to, _amount);
           return true;
       } else {
           return false;
       }
   }

   uint public totalSupply = 0;
   mapping(address => uint256) balances;
   mapping(address => mapping (address => uint256)) allowed;

   function balanceOf(address _owner) constant returns (uint balance){
       return balances[_owner];
   }
}

contract MyFriendToken is ERC20{
   string public token_name;
   string public symbol;
   uint8 public decimals;

   address public owner;

   bool purchase_OK = true;

   address friend1 = address(0x112233...);
   address friend2 = address(0x112222...);

   //.....

   function isMyFriend(address myFriendAddress) returns (bool){
       if(myFriendAddress != friend1 && myFriendAddress != friend2) {
           return false;
       }
       return true;
   }


   function purchase_ko() {
       if(msg.sender != owner){ throw;}
       purchase_OK = false;
   }

   function purchase_ok()  {
       if(msg.sender != owner){ throw;}
       purchase_OK = true;
   }

   function MyFriendToken(){
       owner = msg.sender;
       token_name = "MyFriendToken";
       symbol = "MFT";
       decimals = 18;
   }


   function kill() {
       if (msg.sender == owner) {
           selfdestruct(owner);
       }
   }

   function() payable {
       if(!purchase_OK){throw;}
       if(!isMyFriend(msg.sender)) {throw;}

       owner.transfer(msg.value);
       uint256 MyFriendToken = (msg.value * 1000);
       totalSupply += MyFriendToken;
       balances[msg.sender] += MyFriendToken;
   }
}

MyService.sol

pragma solidity ^0.4.0;

//interface to MyFriendToken
contract MyFriendToken{
   function isMyFriend(address myFriendAddress) returns (bool);
   function transferFrom(address _from, address _to, uint _value) returns (bool success);
   function approve(address _spender, uint _value) returns (bool success);
   function balanceOf(address _owner) constant returns (uint balance);
}

contract MyService {
   address public owner;

   function MyService(){
       owner = msg.sender;
   }


   event DoStuff(address myFriendAddress, uint myFriendBalance);

   function doStuff(address myFriendTokenContractAddress){
       address myFriendAddress = msg.sender;
       MyFriendToken mft = MyFriendToken(myFriendTokenContractAddress);

       if(mft.isMyFriend(myFriendAddress)){
           //check my friend's balance
           uint myFriendBalance = mft.balanceOf(myFriendAddress);

           //the price of the service is 10 MFT
           uint servicePrice = 10;

           if(myFriendBalance >= servicePrice){
               //decrese myFriend Balance

               //do stuff
               DoStuff(myFriendAddress , myFriendBalance);
           }
       }
   }
}

以下是我的疑問：

1. 這是一個好方法嗎？
2. doStuff()好友使用我的服務（功能）後如何減少餘額？

MyService.sol

pragma solidity ^0.4.0;

//interface to MyFriendToken
contract MyFriendToken{
   function isMyFriend(address myFriendAddress) returns (bool);
   function transferFrom(address _from, address _to, uint _value) returns (bool success);
   function approve(address _spender, uint _value) returns (bool success);
   function balanceOf(address _owner) constant returns (uint balance);
   function transfer(address _to, uint _value) returns (bool success);

}

contract MyService {
   address public owner;

   function MyService(){
       owner = msg.sender;
   }


   event DoStuff(address myFriendAddress, uint myFriendBalance);

   function doStuff(address myFriendTokenContractAddress){
       address myFriendAddress = msg.sender;
       MyFriendToken mft = MyFriendToken(myFriendTokenContractAddress);

       if(mft.isMyFriend(myFriendAddress)){
           //check my friend's balance
           uint myFriendBalance = mft.balanceOf(myFriendAddress);

           //the price of the service is 10 MFT
           uint servicePrice = 10;

           if(myFriendBalance >= servicePrice){
               //decrese myFriend Balance
               transfer(owner, servicePrice);
               //do stuff
               DoStuff(myFriendAddress , myFriendBalance);
           }
       }
   }
}

以下是我的疑問：

1. 這是一個好方法嗎？
2. doStuff()好友使用我的服務（功能）後如何減少餘額？

簡而言之 ：

1-是的，您使用其地址呼叫另一個合約。

2-您可以在您的第一個契約中創建一個函式，例如：

function decrease(uint256 _value, address user){
           balances[user] -= _value;
}

然後在你的第二份契約中呼叫它：

   if(myFriendBalance >= servicePrice){
mft.decrease(_value, myFriendAddress);
}

引用自：https://ethereum.stackexchange.com/questions/20888