partial class example in NT8 help guide

[dtl-saw]

In the NT8 help guide code breaking changes section you provide this code example for a partial class

namespaceNinjaTrader.NinjaScript.Indicators { publicpartialclassMyMethods // : parent class to inherit from { //Sample method which calculates the delta of two prices publicdoublecalculateDelta(doublefirstPrice,doublesecondPrice) { returnMath.Abs(firstPrice-secondPrice); } //Sample method which prints Position information publicvoidprintPositionInfo(Positionposition) { Print(String.Format("{0}: {1} {2} at {3}",position.Instrument,position.Quantity,position.MarketPosition,position.AveragePrice)); } } }

then give an example of calling one of the methods in this class from another indicator

protectedoverridevoidOnBarUpdate()
{
if(CurrentBar<1)return;

// Use the static calculateDelta method to calculate the difference between the close of each bar
doubledelta=MyMethods.calculateDelta(Close[0],Close[1]);

Print(delta);
}

When I tried this code out I had to add "static" modifier to the calculateDelta method in the MyMethods class.
Is that correct? If so, then can you fix the typo in the help guide.
Otherwise, what do I need to do to make this work without the "static" modifier.

[bltdavid]

You missed the significance of the comment,

[COLOR=#008000][I]// : parent class to inherit from[/I][/COLOR]

You should place the class name of the NinjaScript objects you wish
to augment -- such as "Indicator" or "Strategy". Even then, I agree,
the example looks to be incorrect.

Try learning from the example here:

https://ninjatraderecosystem.com/user-app-share-download/bond-price-markers/

The class name "MyMethods" is not needed, and neither is "static".

[aligator]

You missed the significance of the comment

@NinjaTrader_Paul, bltdavid Can one apply partial class concept to combine BarTypes class and Indicators class?

For example, I want to create a BarTypes (BarTypes Class) add-on to paint the bars based on calculations results from an indicator (Indicator Class).

[bltdavid]

@NinjaTrader_Paul, bltdavid Can one apply partial class concept to combine BarTypes class and Indicators class?

For example, I want to create a BarTypes (BarTypes Class) add-on to paint the bars based on calculations results from an indicator (Indicator Class).

No.

This would require classes be able to inherit from multiple base classes, a feature
which is not supported in C#. Yes, C# allows multiple inheritance from interfaces,
but an interface is not a class.

You may still be able to achieve what you want, but you cannot inherit from both
Indicator and BarsType -- pick one, fake the other.

[bltdavid]

For example, I want to create a BarTypes (BarTypes Class) add-on to paint the bars based on calculations results from an indicator (Indicator Class).

Paint the bars?
Based upon calculations from an indicator?

Sounds like hundreds of other indicators -- by definition, your idea already fits well in the Indicator class model.

[aligator]

No.

This would require classes be able to inherit from multiple base classes, a feature
which is not supported in C#. Yes, C# allows multiple inheritance from interfaces,
but an interface is not a class.

You may still be able to achieve what you want, but you cannot inherit from both
Indicator and BarsType -- pick one, fake the other.

Thanks bltdavid,

I am not familiar with "fake the other".

Let's say I want a to create a BarType that would paint the bars in two colors based on RSI() being > 50 or < 50. How would one "fake" (or call) the results from the indicator RSI?

[bltdavid]

I am not familiar with "fake the other".

Sorry, 'fake it' is an old-timer's software engineering inside joke.

That just means re-implement portions of the other thing that you couldn't
use directly -- which, frankly, is why some (most?) of those other things in
the C# language are interfaces, and not classes.

In fact, that's exactly what a C# interface is -- an interface mandates that
you provide an implementation for the methods it defines -- so an interface is
giving a voice (sort of) to that old-fashioned technique I used to call 'faking it'.

Let's say I want a to create a BarType that would paint the bars in two colors based on RSI() being > 50 or < 50. How would one "fake" (or call) the results from the indicator RSI?

Using a BarsType?
I have no idea.

Using an Indicator?
Dead simple.

As you describe it, your choices:
1. Create an indicator to paint the bars from RSI values.
2. Create a BarsType to paint the bars from RSI values.

I don't think #2 is even possible.
That's just not how it's done.

Why do you want to use a BarsType?
This approach seems backwards.
Use #1 instead.

[bltdavid]

We're getting a bit off-topic here, I think ...