Universal Expert Advisor scheme - library for MetaTrader 4

Time to time I get a new idea about some new strategy to implement and to see results in strategy tester. Before, I still copied my previous EA and deleted all unwanted stuff
and added my new stuff, so the result was new EA. Some time ago I find a better way for me. I developed a template or scheme for most of my future EAs.
This happened when I was thinkink about more strategies in one EA and about switching between them, according to a period (trend, choppy,... ).
I needed EA scheme that would allow me to have whole "action" code together and whole "strategy" code together. I came to a scheme I want to share with you today.

Main structure of this EA is following:

ActionCode - this contains code independent of strategy implemented in this EA
StrategyCode - this contains whole strategy code

Everything, ActionCode part has to decide to do, is asked by calling StrategyCode part, which returns a result, which can be executed again by universal ActionCode part.

ActionCode Part

int   _STRATEGY_NUMBER              = 1;

#define     _OPEN_LONG                    1
#define     _OPEN_SHORT                   2
#define     _CLOSE_LONG                   3
#define     _CLOSE_SHORT                  4
#define     _GET_LONG_STOPLOSS_PRICE      5
#define     _GET_SHORT_STOPLOSS_PRICE     6
#define     _GET_LONG_TAKEPROFIT_PRICE    7
#define     _GET_SHORT_TAKEPROFIT_PRICE   8
#define     _GET_LOTS                     9
#define     _GET_TRAILED_STOPLOSS_PRICE   10
#define     _GET_TRAILED_TAKEPROFIT_PRICE 11
#define     _GET_TRADED_TIMEFRAME         12
#define     _OPEN_PENDING_BUY_STOP        13
#define     _OPEN_PENDING_SELL_STOP       14
#define     _OPEN_PENDING_BUY_LIMIT       15
#define     _OPEN_PENDING_SELL_LIMIT      16
#define     _GET_PENDING_BUY_STOP_PRICE   17
#define     _GET_PENDING_SELL_STOP_PRICE  18
#define     _GET_PENDING_ORDER_EXPIRATION 19

int start()
{
   double            Stoploss          = 0;
   double            TakeProfit        = 0;
   
   if(LastBarTraded())
      return(0);

   if(OrdersTotal() > 0)
   {
      Stoploss = Strategy(_STRATEGY_NUMBER, _GET_TRAILED_STOPLOSS_PRICE);
      TakeProfit = Strategy(_STRATEGY_NUMBER, _GET_TRAILED_TAKEPROFIT_PRICE);
   
      if(Stoploss != 0 || TakeProfit != 0)
         ModifyAllPositions(_MAGICNUMBER, Stoploss, TakeProfit);

      if(Strategy(_STRATEGY_NUMBER, _CLOSE_LONG) == 1)
         CloseAllLongPositions(_MAGICNUMBER);
      if(Strategy(_STRATEGY_NUMBER, _CLOSE_SHORT) == 1)
         CloseAllShortPositions(_MAGICNUMBER);
   }
   

   if(!TradeAllowed(1))
      return(0);

   if(Strategy(_STRATEGY_NUMBER, _OPEN_LONG) == 1)
      OpenPosition(false, Strategy(_STRATEGY_NUMBER, _GET_LOTS), Strategy(_STRATEGY_NUMBER, _GET_LONG_STOPLOSS_PRICE), 
      Strategy(_STRATEGY_NUMBER, _GET_LONG_TAKEPROFIT_PRICE), 3, _MAGICNUMBER);
   if(Strategy(_STRATEGY_NUMBER, _OPEN_SHORT) == 1)
      OpenPosition(true, Strategy(_STRATEGY_NUMBER, _GET_LOTS), Strategy(_STRATEGY_NUMBER, _GET_SHORT_STOPLOSS_PRICE), 
      Strategy(_STRATEGY_NUMBER, _GET_SHORT_TAKEPROFIT_PRICE), 3, _MAGICNUMBER);

   if(Strategy(_STRATEGY_NUMBER, _OPEN_PENDING_BUY_STOP) == 1)
      OpenPendingPosition(false, Strategy(_STRATEGY_NUMBER, _GET_LOTS), Strategy(_STRATEGY_NUMBER, _GET_PENDING_BUY_STOP_PRICE), 
      Strategy(_STRATEGY_NUMBER, _GET_LONG_STOPLOSS_PRICE), Strategy(_STRATEGY_NUMBER, _GET_LONG_TAKEPROFIT_PRICE), 3, _MAGICNUMBER, 
      Strategy(_STRATEGY_NUMBER, _GET_PENDING_ORDER_EXPIRATION));
   if(Strategy(_STRATEGY_NUMBER, _OPEN_PENDING_SELL_STOP) == 1)
      OpenPendingPosition(true, Strategy(_STRATEGY_NUMBER, _GET_LOTS), Strategy(_STRATEGY_NUMBER, _GET_PENDING_SELL_STOP_PRICE), 
      Strategy(_STRATEGY_NUMBER, _GET_SHORT_STOPLOSS_PRICE), Strategy(_STRATEGY_NUMBER, _GET_SHORT_TAKEPROFIT_PRICE), 3, _MAGICNUMBER, 
      Strategy(_STRATEGY_NUMBER, _GET_PENDING_ORDER_EXPIRATION));

   return(0);
}

StrategyCode part

double Strategy(int STRATEGY, int COMMAND)
{
   switch(STRATEGY)
   {
// Short description of strategy
      case 1:
      {
         return(Strategy_001(COMMAND));
      }
// Short description of strategy
      case 2:
      {
         return(Strategy_002(COMMAND));
      }

//...

// Short description of strategy
      case 99:
      {
         return(Strategy_099(COMMAND));
      }
   }

   return(0);
}


double Strategy_001(int COMMAND)
{
   string   _SYMBOL        = Symbol();
   int      _TIMEFRAME     = getStrategyTimeframeByNumber(_STRATEGY_TIMEFRAME);
         
   double   result         = 0;
   
   int      i;

   switch(COMMAND)
   {
      case _OPEN_LONG:
      {
//         break;

//         if(!OpenNewBar())
//            break;

         if(Open long condition is true)
            result = 1;

         break;
      }
      case _OPEN_SHORT:
      {
//         break;

//         if(!OpenNewBar())
//            break;

         if(Open short condition is true)
            result = 1;

         break;
      }
      case _CLOSE_LONG:
      {
//         break;

         if(Close long condition is true)
            result = 1;
            
            break;
      }
      case _CLOSE_SHORT:
      {
//         break;

         if(Close short condition is true)
            result = 1;
            
            break;
      }
      case _GET_LONG_STOPLOSS_PRICE:
      {
//         break;

         result = Long SL price
         
         break;
      }
      case _GET_SHORT_STOPLOSS_PRICE:
      {
//         break;

         result = Short SL price
         
         break;
      }
      case _OPEN_PENDING_BUY_STOP:
      {
         break;
      }
      case _OPEN_PENDING_SELL_STOP:
      {
         break;
      }
      case _GET_PENDING_BUY_STOP_PRICE:
      {
         break;
      }
      case _GET_PENDING_SELL_STOP_PRICE:
      {
         break;
      }
      case _GET_LONG_TAKEPROFIT_PRICE:
      {
         break;
      }
      case _GET_SHORT_TAKEPROFIT_PRICE:
      {
         break;
      }
      case _GET_TRAILED_STOPLOSS_PRICE:
      {
         break;
      }      
      case _GET_TRAILED_TAKEPROFIT_PRICE:
      {
         break;
      }
      case _GET_LOTS:
      {
         result = Lot amount;

         break;
      }
      case _GET_TRADED_TIMEFRAME:
      {
         result = _TIMEFRAME;

         break;
      }
      case _GET_PENDING_ORDER_EXPIRATION:
      {
         break;
      }
   }
      
   return(result);
}

You can see that implementation of new strategy in this scheme is very easy. Just put a new CASE in Strategy() function and add new function Strategy_NNN() with implemented strategy rules.

This scheme does not fit to any strategy, just to ones, which open one position at time and have a standard "workflow".

As an example I attach complete code with few loosing strategy implemented (see attached code)