casting error?

[td_910]

Hello td_910,

private string unique = string.Empty;
private int barIndex;

In OnStateChange():
else if (State == State.DataLoaded)
{
unique = Guid.NewGuid().ToString();
}

In OnBarUpdate():
// draw a dot
if (State == State.Historical && CurrentBar == Count - 10)
{
Draw.Dot(this, string.Format("dot{0}{1}", unique, CurrentBar), true, 0, High[0] + 3 * TickSize, Brushes.Blue);
barIndex = CurrentBar;
}

loop through a copy of the drawing objects collection (which won't be modified while we're looping)
List<IDrawingTool> objs = DrawObjects.ToList();
for (int i = 0; i < objs.Count; i++)
{
IDrawingTool obj = objs[i];
Print(obj.Tag);

Print(string.Format("dot{0}{1}\r\n", unique, barIndex));
// if its the drawing object i was looking for, remove it
if (obj.Tag == string.Format("dot{0}{1}", unique, barIndex))
RemoveDrawObject(obj.Tag);
}

Thank You!

But this approach wouldn't be useful in the code snippet with the if statement I posted above.

What do you think of the idea to replace the "normal" null check with that method, that uses threadsafe list copy, I posted above?

https://ninjatrader.com/support/forum/forum/ninjatrader-8/indicator-development/1052257-casting-error?p=1062857#post1062857

[NinjaTrader_ChelseaB]

Hello td_910,

This would remove a drawing object if the tag name matches a specific name.

If this is not what you are wanting to achieve, could you provide further detail about what you would like to achieve?

[td_910]

Hi Chelsea,

I'd like to replace e.g. a statement like that:

if (DrawObjects["Thumbs_DT"+(CurrentBar-2)] == null) do something[B][B][B][B][B][B][B][B][B][B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B]

with

if (DrawObjectsCheck["Thumbs_DT"+(CurrentBar-2)] == null) do something[B][B][B][B][B][B][B][B][B][B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B]

then I'm able to replace all DrawObjects checks with search&replace in my code, which would be hundreds I'd like to us this method

        // Loops through the DrawObjects collection via a threadsafe list copy         public string DrawObjectsCheck(string DrawObjectTag)         {             foreach(var tool in DrawObjects.ToList())             {                 if (tool.Tag == DrawObjectTag)                 {                     return DrawObjectTag;                 }             }             return null;         }  [B][B][B][B][B][B][B][B][B][B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B]

[NinjaTrader_ChelseaB]

Hello td_910,

Is DrawObjectsCheck a list copy of DrawObjects.ToList()?

A List<IDrawingTool> object is not going to have index keys like a dictionary..

With multiple instances of the indicator on the chart, using key indexes in the actual DrawObjects() collection and removing objects will cause a collection modified error.

The code of the DrawObjectsCheck method appears to return a tag name. I'm not certain what returning this tag is meant to be used for.

[td_910]

Hi Chelsea,

The tag name is just a string, that is returned, to be different than null, so I can just search and replace in the existing code

Since there is a list copy created with each method call and the tags have a unique string, why would there be a "a collection modified error"

        // Loops through the DrawObjects collection via a threadsafe list copy
        public string DrawObjectsCheck(string DrawObjectTag)
        {
            foreach(var tool in DrawObjects.ToList())
            {
                if (tool.Tag == DrawObjectTag)
                {
                    return DrawObjectTag;
                }
            }
            return null;
        }

[NinjaTrader_ChelseaB]

Hello td_910,

Looping through a list copy of the DrawObjects is fine to do.

Specifically it's using a key index with the actual DrawObjects collection that would cause the error.

The code you have posted above I would not expect to cause an error.

[td_910]

Hi Chelsea,

I didn't get this (I'm not enough of a progammer, yet ;-)) :

Specifically it's using a key index with the actual DrawObjects collection that would cause the error.

Good to hear, so I can go ahaed and modify the code for all my indicators.
Thanks for your help.

Hello td_910,

Looping through a list copy of the DrawObjects is fine to do.

Specifically it's using a key index with the actual DrawObjects collection that would cause the error.

The code you have posted above I would not expect to cause an error.