90 lines
2.5 KiB
MQL5
90 lines
2.5 KiB
MQL5
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//+------------------------------------------------------------------+
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//| ThisCallback.mq5 |
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//| Copyright 2021, MetaQuotes Ltd. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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class Manager; // forward declaration
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//+------------------------------------------------------------------+
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//| Class for manageable objects |
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//+------------------------------------------------------------------+
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class Element
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{
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Manager *owner;
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public:
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Element(Manager &t): owner(&t) { }
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void doMath()
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{
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const int N = 1000000;
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for(int i = 0; i < N; ++i)
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{
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if(i % (N / 20) == 0)
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{
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// pass self into the owner's method
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owner.progressNotify(&this, i * 100.0f / N);
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}
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// ... lot of calculations
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}
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owner.progressNotify(&this, 100.0f); // complete
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}
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string getMyName() const
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{
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return typename(this);
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}
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};
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//+------------------------------------------------------------------+
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//| Manager |
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//+------------------------------------------------------------------+
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class Manager
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{
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Element *elements[1]; // should be dynamic array
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public:
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~Manager()
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{
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// loop through all elements
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// ...
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if(CheckPointer(elements[0]) == POINTER_DYNAMIC)
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{
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delete elements[0];
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}
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}
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Element *addElement()
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{
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// find empty slot in the elements array
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// ...
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// pass self into the manageable object's consturctor
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elements[0] = new Element(this);
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return elements[0];
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}
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void deleteElement(Element *)
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{
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// ...
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}
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void progressNotify(Element *e, const float percent)
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{
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// Manager selects notification method:
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// display, print, send over Internet, etc
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Print(e.getMyName(), "=", percent);
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}
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};
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//+------------------------------------------------------------------+
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//| Script program start function |
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//+------------------------------------------------------------------+
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void OnStart()
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{
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Manager manager;
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manager.addElement().doMath();
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// ...
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}
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//+------------------------------------------------------------------+
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