Abstract base class for indicator -> compile error

[Klaus Hengher]

Hi,

I have an abstract base class for some indicators.
public abstract class MTF_core : Indicator, ICustomTypeDescriptor

The problem is that for this abstract indicator the editor also generates automatic code

#region NinjaScript generated code. Neither change nor remove. ....

After generation of code there is compile error, becuase it is not possible to generate abstract object.

MTF_core.cs Es konnte keine Instanz der abstrakten Klasse oder Schnittstelle 'NinjaTrader.NinjaScript.Indicators.MTF_core' erstellt werden. CS0144

Please exclude abstract indicators for code generation

Thanks
Klaus

[NinjaTrader_ChelseaB]

Hello Klaus,

I have submitted a feature request to our development on your behalf to exclude the generation of NinjaTrader Generated code, when implementing an indicator as an abstract class or when an indicator inherits from an abstract class.

That said, using an abstract class is not supported by NinjaTrader Support to do. My suggestion would be to move the code to a new namespace and call the methods of the class from the indicator, instead of attempting to inherit the entire indicator from an abstract class.

[bltdavid]

using an abstract class is not supported by NinjaTrader

In NT7, you can tell the compiler to skip adding generated code by
removing the Description attribute for the class.

Perhaps the same trick works in NT8?

For example,

bltBaseIndicator.cs:

namespace NinjaTrader.Indicator
{
     /* !!! NO DESCRIPTION -- skip automatic code generation !!! */
    abstract public class bltBaseIndicator : Indicator, ICustomTypeDescriptor
    {
    ...
    }
}

bltFibonacci.cs:

namespace NinjaTrader.Indicator
{
    [Description("This attribute generates NinjaTrader code regions")]
    public class bltFibonacci : bltBaseIndicator
    {
    ...
    }
}

[NinjaTrader_ChelseaB]

Hello,

A workaround is to add the script to the Addons folder instead of the Indicator or Strategy folder. Any scripts in the Addon folder are still compiled but no NinjaScript code is auto generated.

[mrlogik]

Hi guys,

I have a similar, but opposite, issue.

I have a base class, maBase, which inherits from your standard Indicator class. I then have another indicator, lets call it maEma, which inherits from maBase.

When I compile maEma inheriting from maBase, none of the NinjaScript generated Code is created, whereas if I change maEma to inherit from Indicator, it is.

Is there a reason why the auto generated code isn't created when I inherit from maBase, which in turn inherits from Indicator? Is there a way I can force it to auto generate the code, as it is technically an indicator at this second level of inheritance from Indicator.

As always, Thanks!

[NinjaTrader_ChelseaB]

Hi mrlogik,

Do you have a shell indicator exported that demonstrates?

Are you compiling the indicator from the NinjaScript Editor?

[mrlogik]

Hi Chelsea,

I am compiling within the NT editor. I figured it out.

It appears if you have //Indicator after the inherited class name, NT sees the word Indicator and auto generates the code.

For example, my base class is

namespace NinjaTrader.NinjaScript.Indicators
{
    public class testBase : Indicator
    {
    }
}

The class inheriting is

namespace NinjaTrader.NinjaScript.Indicators
{
    public class testInherited : testBase 
    {
    }
}

If I keep the testInherited class as is, and compile, the auto code will not generate.

However, if I add a //Indicator after testBase, it will. See below

namespace NinjaTrader.NinjaScript.Indicators
{
    public class testInherited : testBase  //Indicator
    {

    }
}

Hope this helps anyone else looking to use inheritance.

Thanks again.
Anthony

[QuantKey_Bruce]

As of 8.0.4 is it now the official NT intention that abstract base classes derived from Indicator should work and should not result in an indicator in the indicator list?

[mrlogik]

Bruce,

An FYI, the base class (mine is not abstract) will show in the indicator list. I simply name it appropriately so a user knows it should be ignored.

[QuantKey_Bruce]

An FYI, the base class (mine is not abstract) will show in the indicator list. I simply name it appropriately so a user knows it should be ignored.

If you make it abstract, it should be omitted from the list, because it cannot be instantiated - at least if it is in the AddOns directory where NinjaScript is not added automatically. It used to be true that if it was in the Indicator directory it would still attempt to add the NinjaScript even if it is abstract (the issue of this thread) however that may have been since corrected.