Use of Objects

• Object types
  • Declarations
  • Creating Instances

Object types

Object types are reference types.

• Declarations

  Object types can only be declared at module scope, and must end with a semicolon.

  You can declare an object type as follows:

  object ObjectTypeName { 
      var fieldName1; 
      var fieldName2;
      var fieldName3;
      function methodName1_assignValueToField1(value){
          this.fieldName1 = value;
      }
      function getTheValueOfField1() { 
          return this.fieldName1;
      }
  };

  You can define constructor and destructor:

  const objList = EUDArray(100);
  var objCount = 0;
  object Obj {
      var a, b, c;
      var index;
      function constructor(a, b, c) {
          this.a = a;
          this.b = b;
          this.c = c;
  
          this.index = objCount;
          objList[objCount] = this;
          objCount++;
      }
      function destructor() {  // runs on Obj.free(instance)
          objCount--;
          const lastObj = objList[objCount];
          objList[this.index] = lastObj;
      }
  };
  
  const staticObj = Obj(1, 2, 3);
  const dynObj = Obj.alloc(1, 2, 3);

  (epScript object types usually also have a static constructor method constructor_static, but its internal memory allocation range is constrained.)

  The following declares a Date object type

  object Date {
      var year, month, day, hour, minute, second;
      /***
       * weekday: {0 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday}
       * @type {number}
       * @public
       */
      var weekday;
  
      function update_timestamp(unixTimestamp) {
          const MONTH_DAYS = EUDArray(list(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31));
          var year, month, day = 1970, 1, 1;
          var days, seconds = div(unixTimestamp, 86400);
          const weekday = (days + 4) % 7;
  
          while (true) {
              for (var m = 0 ; m < 12 ; m++) {
                  var daysInMonth = maskread_epd(EPD(MONTH_DAYS) + m, 31);
                  // January of leap year (year is multiple of 4)
                  if (m == 0 && year.ExactlyX(0, 3)) daysInMonth += 1;
                  if (days < daysInMonth) {
                      day = days + 1;
                      days = 0;
                      break;
                  }
                  days -= daysInMonth;
                  month += 1;
              }
              EUDSetContinuePoint();
              if (days == 0) break;
              month = 1;
              year += 1;
          }
          const hour, minuteAndSecond = div(seconds, 3600);
          const minute, second = div(minuteAndSecond, 60);
  
          this.year = year;
          this.month = month;
          this.day = day;
          this.hour = hour;
          this.minute = minute;
          this.second = second;
          this.weekday = weekday;
      }
  };

• Creating Instances

  • There are two ways to create an object instance:
    • Static initialization: const object1 = ObjectTypeName();
    • Dynamic initialization: const object1 = ObjectTypeName.alloc(); You can pass it to any scope for use. Remember to use ObjectTypeName.free(object1); to free the memory it occupies when done.

  The following is an example of using the Date object instance:

  function afterTriggerExec() {
  
      var timestamp;
      var previousSysTime;
      const newSysTime = dwread(0x51CE8C);
      once {
          timestamp = dwread(0x6D0F38);  // game start timestamp
          previousSysTime = newSysTime;
      }
      static var cumulativeSysTime = 0;
      cumulativeSysTime += (previousSysTime - newSysTime);  // time difference
      previousSysTime = newSysTime;
  
      const date = Date();
  
      if (cumulativeSysTime >= 1000) {
          const second, millisecond = div(cumulativeSysTime, 1000);
          cumulativeSysTime = millisecond;
          timestamp += second;
          // date.update_timestamp(timestamp);
          date.update_timestamp(8 * 3600 + timestamp);
      }
  
      const weekdayToName = function (weekday) {
          switch (weekday) {
              case 0: return EPD(Db("Sun"));
              case 1: return EPD(Db("Mon")); 
              case 2: return EPD(Db("Tue"));
              case 3: return EPD(Db("Wed"));
              case 4: return EPD(Db("Thu"));
              case 5: return EPD(Db("Fri"));  
              case 6: return EPD(Db("Sat"));
          }
      };
  
      printAllAt(10, "\x13\x04CST : {}-{}-{}({:t} ) {}:{}:{}",
          date.year, date.month, date.day, weekdayToName(date.weekday), date.hour, date.minute, date.second);
  
  }