Solidity 合约调用合约

原文地址：https://medium.com/@k3no/making-a-birthday-contract-858fd3f63618

先将datetime合约部署：https://github.com/pipermerriam/ethereum-datetime

pragma solidity ^0.4.;

contract DateTime {
        /*
         *  Date and Time utilities for ethereum contracts
         *
         */
        struct _DateTime {
                uint16 year;
                uint8 month;
                uint8 day;
                uint8 hour;
                uint8 minute;
                uint8 second;
                uint8 weekday;
        }

        uint constant DAY_IN_SECONDS = ;
        uint constant YEAR_IN_SECONDS = ;
        uint constant LEAP_YEAR_IN_SECONDS = ;

        uint constant HOUR_IN_SECONDS = ;
        uint constant MINUTE_IN_SECONDS = ;

        uint16 constant ORIGIN_YEAR = ;

        function isLeapYear(uint16 year) public pure returns (bool) {
                if (year %  != ) {
                        return false;
                }
                if (year %  != ) {
                        return true;
                }
                if (year %  != ) {
                        return false;
                }
                return true;
        }

        function leapYearsBefore(uint year) public pure returns (uint) {
                year -= ;
                return year /  - year /  + year / ;
        }

        function getDaysInMonth(uint8 month, uint16 year) public pure returns (uint8) {
                if (month ==  || month ==  || month ==  || month ==  || month ==  || month ==  || month == ) {
                        return ;
                }
                else if (month ==  || month ==  || month ==  || month == ) {
                        return ;
                }
                else if (isLeapYear(year)) {
                        return ;
                }
                else {
                        return ;
                }
        }

        function parseTimestamp(uint timestamp) internal pure returns (_DateTime dt) {
                uint secondsAccountedFor = ;
                uint buf;
                uint8 i;

                // Year
                dt.year = getYear(timestamp);
                buf = leapYearsBefore(dt.year) - leapYearsBefore(ORIGIN_YEAR);

                secondsAccountedFor += LEAP_YEAR_IN_SECONDS * buf;
                secondsAccountedFor += YEAR_IN_SECONDS * (dt.year - ORIGIN_YEAR - buf);

                // Month
                uint secondsInMonth;
                for (i = ; i <= ; i++) {
                        secondsInMonth = DAY_IN_SECONDS * getDaysInMonth(i, dt.year);
                        if (secondsInMonth + secondsAccountedFor > timestamp) {
                                dt.month = i;
                                break;
                        }
                        secondsAccountedFor += secondsInMonth;
                }

                // Day
                for (i = ; i <= getDaysInMonth(dt.month, dt.year); i++) {
                        if (DAY_IN_SECONDS + secondsAccountedFor > timestamp) {
                                dt.day = i;
                                break;
                        }
                        secondsAccountedFor += DAY_IN_SECONDS;
                }

                // Hour
                dt.hour = getHour(timestamp);

                // Minute
                dt.minute = getMinute(timestamp);

                // Second
                dt.second = getSecond(timestamp);

                // Day of week.
                dt.weekday = getWeekday(timestamp);
        }

        function getYear(uint timestamp) public pure returns (uint16) {
                uint secondsAccountedFor = ;
                uint16 year;
                uint numLeapYears;

                // Year
                year = uint16(ORIGIN_YEAR + timestamp / YEAR_IN_SECONDS);
                numLeapYears = leapYearsBefore(year) - leapYearsBefore(ORIGIN_YEAR);

                secondsAccountedFor += LEAP_YEAR_IN_SECONDS * numLeapYears;
                secondsAccountedFor += YEAR_IN_SECONDS * (year - ORIGIN_YEAR - numLeapYears);

                while (secondsAccountedFor > timestamp) {
                        if (isLeapYear(uint16(year - ))) {
                                secondsAccountedFor -= LEAP_YEAR_IN_SECONDS;
                        }
                        else {
                                secondsAccountedFor -= YEAR_IN_SECONDS;
                        }
                        year -= ;
                }
                return year;
        }

        function getMonth(uint timestamp) public pure returns (uint8) {
                return parseTimestamp(timestamp).month;
        }

        function getDay(uint timestamp) public pure returns (uint8) {
                return parseTimestamp(timestamp).day;
        }

        function getHour(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp /  / ) % );
        }

        function getMinute(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp / ) % );
        }

        function getSecond(uint timestamp) public pure returns (uint8) {
                return uint8(timestamp % );
        }

        function getWeekday(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp / DAY_IN_SECONDS + ) % );
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, , , );
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, hour, , );
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour, uint8 minute) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, hour, minute, );
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour, uint8 minute, uint8 second) public pure returns (uint timestamp) {
                uint16 i;

                // Year
                for (i = ORIGIN_YEAR; i < year; i++) {
                        if (isLeapYear(i)) {
                                timestamp += LEAP_YEAR_IN_SECONDS;
                        }
                        else {
                                timestamp += YEAR_IN_SECONDS;
                        }
                }

                // Month
                uint8[] memory monthDayCounts;
                monthDayCounts[] = ;
                if (isLeapYear(year)) {
                        monthDayCounts[] = ;
                }
                else {
                        monthDayCounts[] = ;
                }
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;
                monthDayCounts[] = ;

                for (i = ; i < month; i++) {
                        timestamp += DAY_IN_SECONDS * monthDayCounts[i - ];
                }

                // Day
                timestamp += DAY_IN_SECONDS * (day - );

                // Hour
                timestamp += HOUR_IN_SECONDS * (hour);

                // Minute
                timestamp += MINUTE_IN_SECONDS * (minute);

                // Second
                timestamp += second;

                return timestamp;
        }
}

然后获取datetime utility的地址，再部署另一个合约：

pragma solidity ^ 0.4.;
contract DateTime {
        function getYear(uint timestamp) public constant returns (uint16);
        function getMonth(uint timestamp) public constant returns (uint8);
        function getDay(uint timestamp) public constant returns (uint8);
}
contract BirthDay {
  uint public bday;
  address public dateTimeAddr = 0xb23e0bfaeedcfce82ea2011f2a2726584e611e57;
  DateTime dateTime = DateTime(dateTimeAddr);
  function BirthDay() public  {
    bday = now;
  }
  function getBirthYear() view public returns (uint16){
      return dateTime.getYear(bday);
  }
  function getBirthMonth() view public returns (uint8){
      return dateTime.getMonth(bday);
  }
  function getBirthDay() view public returns (uint8){
      return dateTime.getDay(bday);
  }
}