array operator [] vs value[]

[zweistein]

Hello,

accessing an indicator like SMA I can access the value ofd the currentbar as

double d= INDICATOR(parameter).Value[currentbar]

using the Value property


how is the array [] operator handled in NT?

is the above always the same as:

double d=INDICATOR(parameter)[currentbar]


Best regards
Andreas

[Ralph]

is the above always the same as:

double d=INDICATOR(parameter)[currentbar]

The syntax is rather like this:
double d=INDICATOR(parameter).PropertyArray[currentbar]

INDICATOR(parameter) is a method-call for a method of the Indicator class (base classs of your custom indicator). This method returns a pointer to the related instance of your custom indicator.
.PropertyArray[] is the "getter" of an array property which belongs to the public interface of your custom indicator.

Regards
Ralph

[zweistein]

Hi Ralph,

I tried this:

double a=SMA(3)[0];
double b=SMA(3).Value[0];
//double c=SMA(3).PropertyArray[0];

Print("a="+a.ToString()+"b="+b.ToString());

but .PropertyArray[0] gives a compile error and was therefore commented.

In my example a equals b, therfore the array operator [] is mapped to the getter .Value[0]

For code elegance I would like to use the array operator [] ,

but is it always mapped to .Value[] ?

What happens if the indicator defines a Property Value.
Will the array operator [] still map to the derived class or will it point to the base class definition of Value?

Please explain the .PropertyArray further.

Thank you
Andreas

[Ralph]

Hi Andreas,

with .PropertyArray I ment an arbitrary name for a poroperty (i.e. myColor). Therefore I misunderstood your question and my previous answer was rubbish anyway.

The Indicator base class creates and stores instances of your custom indicator based on the signature of all members of the public properties. To correct myself: therefore the brackets [] do not have to do anything with the public properties of the custom indicator.

So, the syntax INDICATOR(parameter)[index] looks to me like an indexed class (indexer is the key word here). It is just a guess, but perhaps NT stores the indicator's values (for the bars of a series) by means of indexed classes. I couldn't find and explanation for .Value[index]. You confirmed that it compiles and works properly, so it looks like a synonym for an indexer access. If that's true, I could imagine that it still would be possible to use "Value" as a property name. I am personally wouldn't do that, because "value" is also used as a key word for the set-accessor of a property.

Regards
Ralph