unable to copy the values

[samjesse]

Hi
I often get

Unable to copy the values of the indicator. Error 4806
in the M1 chart and not on other charts.

void SOMECLASS::populate(void)
{
      int copied=CopyRates(_symbol, _period, 0, bars, myRates); 
      if(copied<=0) Print("Error copying price data ",GetLastError());
      stoHandle = iStochastic(_symbol, _period, 34, 3, 9, MODE_SMA, STO_CLOSECLOSE);
      copied=CopyBuffer(stoHandle, 0, 0, bars, stochBuffer);
      if(copied<=0) 
      {
         Alert("Unable to copy the values of the indicator. Error = ", GetLastError(),",  copied =",copied);
      }
}

[Enivid]

If the CopyBuffer() function is called too early after initialization it may copy no data because indicator data is not yet ready. Try calling it in the second occurrence of the OnCalculate(), not the first, if this is an indicator.

[samjesse]

would this create a side effect problem?
i.e. what are the cases when this would result in infinite loop?

   //--- Change this vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
   copied=CopyBuffer(stoHandle, 0, 0, bars, stochBuffer);
   if(copied<=0)
   {
      Alert("Unable to copy the values of the indicator. Error = ", GetLastError(),",  copied =",copied);
   }
   
   //--- To this  vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
   int copied;
   while(copied<=0) copied=CopyBuffer(stoHandle, 0, 0, bars, stochBuffer);

[samjesse]

I noticed from the this code that Sleep(1000) does not really wait 1 second. before the next loop.

Am I doing something wrong?

thx

 for(uchar i=0; i<10; i++)
   {
      int copied=CopyBuffer(stoHandle, 0, 0, bars, stochBuffer);
      if(copied<=0) 
      {
         Sleep(1000);
         Print("sleeping "+i);
      } 
      else 
      {
         i=10;
         Print("copied");
      }

[Enivid]

If that's an indicator, just don't alert the error. I do it like this:

myMA = iMA(NULL, 0, 1, 0, MODE_SMA, AppliedPrice);
if  (CopyBuffer(myMA, 0, rates_total - shift - 1, Len, MAB) != Len) return(0);

You'll know about the error - the indicator just won't draw.

[samjesse]

Originally Posted by Enivid

If that's an indicator, just don't alert the error. I do it like this:

myMA = iMA(NULL, 0, 1, 0, MODE_SMA, AppliedPrice);
if  (CopyBuffer(myMA, 0, rates_total - shift - 1, Len, MAB) != Len) return(0);

You'll know about the error - the indicator just won't draw.

no. I need its value for further coding.

[Enivid]

Then do not run the code that requires the indicator buffer before some time after initialization passes.

[samjesse]

and how do you control the "some time after"? i.e. wait(2 sconds); or sleep() or ... how?

[Enivid]

I'd say 1 tick is enough. If you indicator/EA/script reacts to ticks, there's nothing difficult in that.

[samjesse]

Originally Posted by Enivid

If the CopyBuffer() function is called too early after initialization it may copy no data because indicator data is not yet ready. Try calling it in the second occurrence of the OnCalculate(), not the first, if this is an indicator.

Is there a way to Sleep(); after OnInit() and before OnCalculate? in order to fix this problem?

The reason is, it is not that simple to do CopyBuffer() after one tick given the logic of my code. why?

I have a class object as a Global variable where the constructor calls the populate() for a myRates array and creates iStochastic and does the CopyBuffer() we are dealing with.
OnInit() does nothing with the code except deal with house keeping for plotting and the like.
OnCalculate() recalls the populate() conditionally based on chart bars behavior.

so withing for the "second" tick to CopyBuffer() will need a bit of work, specially when I have to deal with "at the beginning of OnCalculate().

last_bar_time = SeriesInfoInteger(_Symbol, _Period, SERIES_LASTBAR_DATE);
if(new_bar_time == last_bar_time) return(rates_total); else new_bar_time = last_bar_time;

since the above 2 lines will never let me have the second tick to do CopyBuffer().