OnCalculate function

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I am building a new indicator using the OnCalculate function for the first time. As I'm going through the logic in my brain, I can't get past the problem of what to do if I have multiple For loops that depend on prev_calculated settings when a recall occurs in the middle of a For loop. For example, a recall of OnCalculate occurs at iteration 162  of For loop 1, and prev_calculated is set at 162 upon re-entry of the OnCalculate function. For loop 1 continues where it was interrupted and completes its job. Here is where I see a problem... For Loop 2 is now using the prev_calculated value of 162 as the starting point, never processing bars 0 through 161. Can someone please shed some light on how to get through this? It may be something simple that I don't understand about how OnCalculate works, but I want to get past this so I can continue with the logic for my Indicator. Thank you in advance!
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OnCalculate Function in Indicator - MQL4 forum
  • www.mql5.com
OnCalculate Function in Indicator - MQL4 forum
 
tegabach:
I am building a new indicator using the OnCalculate function for the first time. As I'm going through the logic in my brain, I can't get past the problem of what to do if I have multiple For loops that depend on prev_calculated settings when a recall occurs in the middle of a For loop. For example, a recall of OnCalculate occurs at iteration 162  of For loop 1, and prev_calculated is set at 162 upon re-entry of the OnCalculate function. For loop 1 continues where it was interrupted and completes its job. Here is where I see a problem... For Loop 2 is now using the prev_calculated value of 162 as the starting point, never processing bars 0 through 161. Can someone please shed some light on how to get through this? It may be something simple that I don't understand about how OnCalculate works, but I want to get past this so I can continue with the logic for my Indicator. Thank you in advance!
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Not sure where to reply if your reply ends in mql4.com.

No interrupts would appear during any event method, but timeout when closing the entire GUI. All history buffers stay unchanged until the event method finishes.

 
Ovo Cz:

Not sure where to reply if your reply ends in mql4.com.

No interrupts would appear during any event method, but timeout when closing the entire GUI. All history buffers stay unchanged until the event method finishes.

Thank you! Excuse my ignorance, I am new to MQL4 programming... Can you elaborate on the term 'event method'? From the example given below, if you don't mind, can you identify the event methods? Thank you!

//+------------------------------------------------------------------+
//| Ichimoku Kinko Hyo                                               |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   int    i,k,pos;
   double high_value,low_value;
//---
   if(rates_total<=InpTenkan || rates_total<=InpKijun || rates_total<=InpSenkou)
      return(0);
//--- counting from 0 to rates_total
   ArraySetAsSeries(ExtTenkanBuffer,false);
   ArraySetAsSeries(ExtKijunBuffer,false);
   ArraySetAsSeries(ExtSpanA_Buffer,false);
   ArraySetAsSeries(ExtSpanB_Buffer,false);
   ArraySetAsSeries(ExtChikouBuffer,false);
   ArraySetAsSeries(ExtSpanA2_Buffer,false);
   ArraySetAsSeries(ExtSpanB2_Buffer,false);
   ArraySetAsSeries(open,false);
   ArraySetAsSeries(high,false);
   ArraySetAsSeries(low,false);
   ArraySetAsSeries(close,false);
//--- initial zero
   if(prev_calculated<1)
     {
      for(i=0; i<InpTenkan; i++)
         ExtTenkanBuffer[i]=0.0;
      for(i=0; i<InpKijun; i++)
         ExtKijunBuffer[i]=0.0;
      for(i=0; i<ExtBegin; i++)
        {
         ExtSpanA_Buffer[i]=0.0;
         ExtSpanA2_Buffer[i]=0.0;
        }
      for(i=0; i<InpSenkou; i++)
        {
         ExtSpanB_Buffer[i]=0.0;
         ExtSpanB2_Buffer[i]=0.0;
        }
     }
//--- Tenkan Sen
   pos=InpTenkan-1;
   if(prev_calculated>InpTenkan)
      pos=prev_calculated-1;
   for(i=pos; i<rates_total; i++)
     {
      high_value=high[i];
      low_value=low[i];
      k=i+1-InpTenkan;
      while(k<=i)
        {
         if(high_value<high[k])
            high_value=high[k];
         if(low_value>low[k])
            low_value=low[k];
         k++;
        }
      ExtTenkanBuffer[i]=(high_value+low_value)/2;
     }
//--- Kijun Sen
   pos=InpKijun-1;
   if(prev_calculated>InpKijun)
      pos=prev_calculated-1;
   for(i=pos; i<rates_total; i++)
     {
      high_value=high[i];
      low_value=low[i];
      k=i+1-InpKijun;
      while(k<=i)
        {
         if(high_value<high[k])
            high_value=high[k];
         if(low_value>low[k])
            low_value=low[k];
         k++;
        }
      ExtKijunBuffer[i]=(high_value+low_value)/2;
     }
//--- Senkou Span A
   pos=ExtBegin-1;
   if(prev_calculated>ExtBegin)
      pos=prev_calculated-1;
   for(i=pos; i<rates_total; i++)
     {
      ExtSpanA_Buffer[i]=(ExtKijunBuffer[i]+ExtTenkanBuffer[i])/2;
      ExtSpanA2_Buffer[i]=ExtSpanA_Buffer[i];
     }
//--- Senkou Span B
   pos=InpSenkou-1;
   if(prev_calculated>InpSenkou)
      pos=prev_calculated-1;
   for(i=pos; i<rates_total; i++)
     {
      high_value=high[i];
      low_value=low[i];
      k=i+1-InpSenkou;
      while(k<=i)
        {
         if(high_value<high[k])
            high_value=high[k];
         if(low_value>low[k])
            low_value=low[k];
         k++;
        }
      ExtSpanB_Buffer[i]=(high_value+low_value)/2;
      ExtSpanB2_Buffer[i]=ExtSpanB_Buffer[i];
     }
//--- Chikou Span
   pos=0;
   if(prev_calculated>1)
      pos=prev_calculated-1;
   for(i=pos; i<rates_total; i++)
      ExtChikouBuffer[i]=close[i];
//---
   return(rates_total);
  }
//+------------------------------------------------------------------+
 

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Hello,

Please use the SRC button when you post code. Thank you.


This time, I edited it for you.


 
tegabach:

Thank you! Excuse my ignorance, I am new to MQL4 programming... Can you elaborate on the term 'event method'? From the example given below, if you don't mind, can you identify the event methods? Thank you!

OnCalculate is an "event method".

See https://docs.mql4.com/runtime/event_fire

Client Terminal Events - MQL4 Documentation
  • docs.mql4.com
Client Terminal Events - MQL4 Documentation
 
Alain Verleyen:

OnCalculate is an "event method".

See https://docs.mql4.com/runtime/event_fire

Thank you! That explains it all. There is no interrupt during a pass of OnCalculate, so the process ignores new ticks of data until control is passed on the Return. My question has been answered, so now I can proceed...
 
tegabach:

Thank you! Excuse my ignorance, I am new to MQL4 programming... Can you elaborate on the term 'event method'? From the example given below, if you don't mind, can you identify the event methods? Thank you!

"Method" is also used to describe a "function", although usually incorrectly many times.  According to what I have read, a function is what you would think, while a method is a specific type of function that specifically operates on an object.  A function can also exist outside of objects, while methods are usually defined within a specific object.
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