C# class or no class... question from newbie

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  Sam Hobbs16y agoPosted Nov 10, 2010, 4:23 PM

  
  In the C# language, it is impossible to have anything outside a class; that is a fundamental design criteria of C#. The designers of C# are object-oriented enthusiasts and they want to emphasize the advantages of object-oriented programming. It is possible to write programs that essentially use global items using a static members but usually it is possible to develop more object-oriented solutions.
   
  You sure are benefiting from the time spent by others to help you. Note that most of what you are asking for help with is already explained very well in articles and books. Forums are usually intended for questions that are not easily answered in the dovumentation and in articles and in books. I hope you can get a good book about C#; it will answer many, many more questions.
• A

  Arthur16y agoPosted Nov 9, 2010, 6:26 PM

  Hi Tony,
  Thanks for your reply. Here's what I was looking for:
  
  void PlotSignals(string direction, int arrowPos, Color arrowColor)
  {
      if (direction == "up")
          DrawDot("up arrow", arrowPos, arrowColor);
      else if (direction == "down")
          DrawDot("down arrow", arrowPos, arrowColor);
  }
  
  // To call...
  
  protected override void OnBarUpdate()
  {
      if (....)
          PlotSignals("up", 2, Color.Green);
      else if (...)
          PlotSignals("down", 2, Color.Red);
  }
  
  Is there a global variable in C# that can hold the values throughout the session and programmer can manipulate with it passing some global values from one program unit to another...? Suppose I have few objects, e.g. some separate windows forms that I'm running in my current session. How can I pass a value from one form to another please? This maybe not a good example but I cannot come up with anything better.
  

  Thank you very much again.
  Art.
  

  
  
• T

  Tony16y agoPosted Nov 9, 2010, 3:29 PM

  
  Hi Art.
  Sorry it took me a while to get back to you. I've been really busy.
  Ok... let's take a step back here. This is what I'm seeing from your last post:
  So you have onBarUpdate() that is currently calling draw() methods based on conditions, like this:
  ^{_{protected void onBarupdate(){
   
    if (some val >= 40 && other val < 0)
    {
             DrawArrowDown(); 
    }}}
  And what you're wanting is some method that you can call that will contain all of the draw() methods like this:
  ^{_{protected void onBarupdate(){
    
   myUltimatDrawMethod(); //This one method would hit several drawMethods().
  }}}
  Is that correct?
  
  Here's a couple questions for you Art. Do all of your draw methods share the same number AND type of parameters? Also, are you needing to call certain draw() methods based on a particular set of parameters?
• A

  Arthur16y agoPosted Nov 5, 2010, 9:14 AM

  Hi,
  This time I'd like to ask about methods. While I'm slowly grasping the concept of classes I'd like to learn about methods please.
  Here's my orig example again:
  
  // this progr. is from charting software - Ninja Trader.
  
  protected override void OnBarUpdate()
  {
  
                if (some val >= 40 && other val < 0)
                  {
                  DrawArrowDown("MyDnArrow" , true, 1, (hh+0.0002), Color.OrangeRed);
                  DrawDiamond("MyDiamond", true, 1, (hh+0.0011), Color.Blue);
                  DrawTriangleDown("MyDownTriangle", true, 1, (hh+0.0013), Color.Blue);
                  }
                 else if (some val < 40... && ... >=30 ...)
                  {
                  DrawArrowDown("MyDnArrow" , true, 1, (hh+0.0002), Color.OrangeRed);
                  DrawDiamond("MyDiamond", true, 1, (hh+0.0011), Color.Blue);
                  DrawTriangleDown("MyDownTriangle", true, 1, (hh+0.0013), Color.Blue);
                  }
  .........
  
  }
  
  In OnBarUpdate() I'm calling methods (Draw...() methods) within if's. I'd like to be able to call my method with all all those Draw...() methods already inside, e.g.:
  
  Method PlotSignals(int arrow_dir, int arrow_position, arrow_color)
  {
  if (arrow_dir == 2) // arrow down then
  {
    DrawArrowDown("MyDnArrow" , true, 1, arrow_pos, arrow_color);
    DrawDiamond(....)
    DrawTriangleDown(....);
  }
  else // arrow_dir == 1 - arrow up
  {
    DrawArrowUp().....
  ......
  }
  }
  
  Then in OnBarUpdate() I'd simply call PlotSignals(pa1, par2....) method with a single statement instead of repeatedly calling Draw...() methods as below:
  
  protected override void OnBarUpdate()
  {
                if (some val >= 40 && other val < 0)
                  {
                    // this method has all inside of it - passing all values for Draw...()
                     PlotSignals(2, 5, arrow_color); // 2 - arrow down, 5 - arrow position on the chart, color...
                  }
                 else if (some val < 40... && ... >=30 ...)
                  {
                     PlotSignals(1, 5, arrow_color); // 1 - arrow UP, 5 - arrow position on the chart, color...
                  }
  .........
  
  }
  
  This is what I'm trying to accomplish and I think is better and simpler/cleaner approach...
  Thank you very much.
  Art.
  
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  Arthur16y agoPosted Nov 3, 2010, 11:55 AM

  Thank you very much, Tony, it makes sense of course. I wish it'd be simpler...
  And Thank you Diego. You guys rule!
  Thank you very much to all again.
  Art.
  
• T

  Tony16y agoPosted Nov 3, 2010, 10:53 AM

  
  Hi Arthur.
  There aren't two nested classes. There's one class and two constructors. Let me explain.
  The class declaration is: public class DrawClass{
  The constructors are:
  public DrawClass()    AND   public DrawClass()
  So in OOP, a class is not the same thing as an object. A class is a blueprint for an object. In order to create an object from a class we have to instantiate it, or better put, create a new object. And that looks like this:
  
  = new ()  - notice the parans here.
  DrawClass myDrawClass = new Drawclass()
  
  When you intantiate an object, you're actually calling the constructor. So....
  
  DrawClass myDrawClass = new DrawClass() - This is hitting the blank constructor.
  DrawClass myDrawClass = new DrawClass() - This is hitting our constructor with parans.
  Constructorrs allow you to pass in values upon creation of the object. Take a person class for example.
  Person myPerson = new Person("Frank", "Smith");
  
  If we had a class called person that had the attributes of 'firstName' and 'lastName', we could create a new object and pass in a first and last name. So then if we needed to GET the values we could then do this:
  
  myPerson.firstName;
  myPerson.lastName;
  And our output would be "Frank Smith". Does this make more sense?
• D

  Diego16y agoPosted Nov 3, 2010, 10:38 AM

  Hi Arthur,
  
  If you want to comment a block you can use
  
  /* block here
  block here */
  
  
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  Arthur16y agoPosted Nov 3, 2010, 9:09 AM

  Thank you very much, Tony. Seems this is what I was looking for. Still have a q:
  public class DrawClass
  {
  ......
  

  Public DrawClass(String _shape, _int id, String _color)
  {
            String shape = _shape;
  ......
  
  
  Why there are two (nested?) classes? Can't I get the same result with one - Public DrawClass()? Is there a way to do what I need w/out classes with some other C# thing with some kind of public... void...? But the main q is about Public DrawClass() - do I really need the public class DrawClass {}... before Public DrawClass()? Is there a way to simplify this more is my question.
  
  And another q. please. Is there a way to comment a block of code in C#? I know how to comment a line - //, but there must be a way to comment more then one line at once.
  
  Thank you very much.
  Art.
  

  
  
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  Tony16y agoPosted Nov 2, 2010, 9:06 PM

  Ok. I think I have a slightly better understanding of what you're looking for. But I think what you need to fully understand is that if you are going to need to trigger certain methods based on conditions like you have posted above, I don't know if you can get much simpler than what you have listed. I can show you another way of calling those methods based on parameters, but again, if you're looking for simplicity, you're already pretty close. :)
  
  Below is one example of each of your methods being called through a class (container).
  
  
  //Class declaration - these are comments btw ;)
  public class DrawClass
  {
  

  //Constructor has the same name as the class
  Public DrawClass()
  {
  

  //This is an empty constructor, just for examples sake.
  Console.WriteLine("This does nothing dude.");
  

  }
  Public DrawClass(String _shape, _int id, String _color)
  {
            String shape = _shape;
            int id = _id;
            String color = _color;
  

  //conditional to confirm shape desired
  if (shape.equals("circle")
  {
     //Call your CircleDraw() method and pass the passed in parameters.
     CircleDraw(shape, id, color);
     Console.WriteLine("This draws a circle");
  }
  if (shape.equals("square")
  {
     //Call your SquareDraw() method and pass the passed in parameters.
     SquareDraw(shape, id, color);
     Console.WriteLine("This draws a square");
  }
  

  }
  

  }
  
  
  Then in your Main() method you would instantiate the object like this.
  
  
  public static void Main()
  {
  
      //here you have your original if statements
  if (....)
   {
      DrawClass drawACircle = new DrawClass(circle, 1, black);
   } 
  
  else if (more ....)
    {
       DrawClass drawASquare = new DrawClass(square,1, purple);
    }
  
  }
  
  You can even call them directly like this