MQL4 - create auto shifting array?

Question

I'm working on a custom indicator...

Double Arrays set as IndexBuffers automatically shift right each time a new bar is created. As do Constants such as Open[], Close[], etc. The reason for this is fairly obvious... the same code can be use when chart is loaded as when the graph updates, without having to recalculate existing bars.

int start()                         
{
   int Counted_bars;
   Counted_bars=IndicatorCounted(); 
   i=Bars-Counted_bars-1;           
   while(i>=0)                      
   {
      IndicatorBuffer[i] = [Some-calculations];
      i--;                          
   }
   return (1);                          
}

Is there a way to declare an array that will also shift automatically along with everything else whenever a new bar is created? Preferably using the Existing API. So like:

enum Range{Low, Mid, high};
Range[] BarRange;  //A Range value corresponding to each bar, calculates in the start loop.

How to keep it in Sync with the other arrays?

Answer 1

Declare a new array and assign it to SetIndexBuffer(number of array,arrayName, INDICATOR_CALCULATIONS) so that to keep in invisible for drawing. It can use array of only double type I am afraid, if you need a struct - then you have to use something else (probably change struct to class and fill in into CArrayObj and check each bar to extend it or to add new element)

Answer 2

Do not panic:

The initial idea of

enum Range{  Low,
             Mid,
             high
             };
     Range[] BarRange;

will ( as-of-2018/Q1 ) go beyond compiler's will to compile such code,

---

Yet:

just a slightly modified approach will fit ( have used vast array-based analytics and augmented-trading tools based on this mechanism ):

#define getLow  0
#define getMid  1
#define getHigh 2

double array_of_almost_structs[][];
    //                         | |
    //                         | +----------+
    //                         |            |
    // fill data as needed  row# ~ bar#, col# ~ { getLow | getMid | getHigh }

So the syntax-limit could be circumvented.

---

CustomIndicator code-units interfacing has additional points:

Given your code-execution unit is expected to be used via a CustomIndicator process-to-process interface, more issues come to get aligned.

The ExpertAdvisor-type of the MQL4/5 code issues a call to iCustom() interfacing proxy.

These details prevent your innovations on the CustomIndicator-type of MQL4/5 code, as the "remote" call-initiator will not be able to properly "pick"-data-elements from any smarter "remote"-storage than the implicitly aligned / addressed by a "nailed"-down plain double array1D[];, "registered" into the distributed CustomIndicator<->ExpertAdvisor data-mation mechanics via a call to SetIndexBuffer( index, array );

Not much to do about this.