Dilemma with Delegates

[dontpanic]

Hi, this is an extension to some work I was doing with NCalc in another thread, but not restricted to it.

I'm trying to implement an array of delegates and I was doing pretty well until I ran into a problem.

the code so far...

// in variables section - my indicator name is WillsMTWave, and FunctionArgs is from class NCalc

private FloatSeries[] wmtPlotValues;

delegate void gwExtendedFunction(FunctionArgs args);
gwExtendedFunction[] gwExtendedFunctions;
GWExprEvaluatorFunctions gwExprEvaluatorFunctions;

public class GWExprEvaluatorFunctions : NinjaTrader.Indicator.WillsMTWave {
public void concaveCB(FunctionArgs args) {
Print(wmtPlotValues[0][0].ToString());
}
}

// in Initialize()

wmtPlotValues = new FloatSeries[PLOTS];

gwExprEvaluatorFunctions = new GWExprEvaluatorFunctions();
gwExtendedFunctions = new gwExtendedFunction[3];
gwExtendedFunctions[0] = new gwExtendedFunction(gwExprEvaluatorFunctions.concav eCB);

// in OnBarUpdate()

// call the delegate
gwExtendedFunctions[0](args);

Now, this actually all works fine (almost), I can call the delegate and get some correct debug out, including the parameters, but the line

Print(wmtPlotValues[0][0].ToString());

is giving the runtime error

Error on calling 'OnBarUpdate' method for indicator 'WillsMTWave' on bar 22: Object reference not set to an instance of an object.

bar 22 is the first bar for which it is called. Now strictly speaking the call gwExtendedFunctions[0](args) is not made from within OnBarUpdate(),
it is actually made from another delegate function that is called from within OnBarUpdate(), I'm not sure if thats significant or not. I can correctly reference wmtPlotValues[0][0] from within OnBarUpdate(), its only when its referenced from the delegate that the error occurs.

Anyone game to tackle this one for me?

Thanks,
will.

[NinjaTrader_MichaelM]

Hello Will,

Thank you for writing in. I am unsure if there is simply a typo in your code. Are you meaning to instantiate the wmtPlotValues FloatSeries using the PLOTS object or are you trying to instantiate a FloatSeries of PLOTS length?
Please try the following:

wmtPlotValues = new FloatSeries(PLOTS);

Please see our help guide here: http://ninjatrader.com/support/helpG...ub=floatseries

Please provide me with more information/code concerning your PLOTS object if you require further investigation.

Thank you in advance.

[dontpanic]

hi, thanks, and sorry for the confusion. PLOTS is a constant defined earlier, I'm creating an array of FloatSeries (of size PLOTS).

Thanks,

edit....

It must have something to do with the array declaration or instantiation, not the scope.

If I do this :-

// in variables section - my indicator name is WillsMTWave, and FunctionArgs is from class NCalc

private FloatSeries[] wmtPlotValues = new FloatSeries[PLOTS];
private int myInt=1;

and in my deletgate the below gives the error I reported earlier :-

public class GWExprEvaluatorFunctions : NinjaTrader.Indicator.WillsMTWave {
public void concaveCB(FunctionArgs args) {
Print(wmtPlotValues[0][0].ToString());
}
}


but this works fine :-

public class GWExprEvaluatorFunctions : NinjaTrader.Indicator.WillsMTWave {
public void concaveCB(FunctionArgs args) {
Print(myInt.ToString());
}
}

[NinjaTrader_MichaelM]

Hello dontpanic,

From what I understand, you are simply not instantiating the FloatSeries correctly. Please try the following:

private FloatSeries[] wmtPlotValues = new FloatSeries[PLOTS];

//... and then somewhere in your code before you try and print anything from wmtPlotValues
for(int i = 0; i < wmtPlotValues.Length; i++)
{
    wmtPlotValues[i] = new FloatSeries(this);
}

If the issue persists, please provide an example code with which I can test this issue.
Thank you in advance.

[dontpanic]

Hi Michael

yes I already have that code in Initialize()

for(int i=0; i<PLOTS; i++) {
wmtPlotValues[i] = new FloatSeries(this, MaximumBarsLookBack.Infinite);
}

I'm already using those dataseries in the indicator and they are working fine. Its just the delegate that is having a problem with it.

Thanks
will.

[NinjaTrader_MichaelM]

Hello Will,

Please provide me with an full code example which illustrates the issue so I can test the issue properly and deliver you with a correct and complete answer. I recommend exporting the code using the export function of NinjaTrader, then attaching the .zip file to your response.

If you do not wish to post the code on the forums, please attach it to an email to platformsupport[AT]ninjatrader[DOT]com with the subject line: "ATTN: Michael M http://www.ninjatrader.com/support/f...ad.php?t=77583 #1376619".

Thank you in advance.