How to: Create Properties with names as values. Part 1/2

[David Lean]

Ever wanted to have your Property give the Trader a dropdown list of values like "Open, Close ..." to choose from rather than asking them to type a number? This is how you do it.

Step 1: Create an Enumerated type

public

enum MAType {

Simple = 0,
Exponential = 1,
Weighted = 2
}

Tip A: Its always good to assign the value 0 to something that will be the default. If you are using these as Flags, make it = "None"
Tip B: You don't have to put any numbers after the name, it is just my preference.
Tip C: You can improve the documentation/intellisense by adding a "///" Prefix prior to the enum value. eg:

///

<summary>Simple Moving Average </summary><returns></returns>

Simple = 0,

Tip D: If you plan on creating Values that you can compare & blend together with logic, use the [Flags] Attribute & assign a value that is represented by single bit. eg 1,2,4,8,16... Zero should indicate no flags are set.

[Flags]
public enum StopType {
None = 0x00,
SAR = 0x01,
CrossOver = 0x02
};

if (myStop && StopType.SAR) { ...}

Tip E: Declare it Outside of your class.
If you don't, you will need to also change the Property Category to prevent it being a public parameter which means it will not be visible to any other parts of Ninja, ie Strategy etc. (I'll make another post on this)

#region My Global Enums
publicenum SymbolType {
Circle = 1,
Square = 2, ...
}
#endregion
// Note: enums are before this line
//This namespace holds all indicators and is required. Do not change it.
namespace NinjaTrader.Indicator
{

Step 2: Create a Property with its value
As this is really just a number. You don't have to do anything special to serialise it. It will save & restore its settings just fine.

[Description("This Property does ...")]
[Category("Parameters")]
[Gui.Design.DisplayName("Moving Average")]
public MAType MovAvgName
{
get { return movAvgName; }
set { movAvgName = value; }
}

<Exceeded post limit, continued in the reply>

[David Lean]

How to: Create Properties with names as values. Part 2/2

Step 3: Declare a local variable to hold the property value

#region Variables
// Wizard generated variables
private MAType movAvgName = MAType.Simple;

Step 4: Use it in your code.
Typically you will use either a switch statement to distinguish between a your many types. A common error is to forget to prefix the value (".Simple") with the enum type ("MAType.")
switch (movAvgName) {
case MAType.Simple: dataMA.Set(SMA(Input,iPeriod)[0]);
break;
case MAType.Weighted: dataMA.Set(WMA(Input,iPeriod)[0]);
break;
}
OR an if statement with a bit mask to AND or OR the result to filter out flags.
if ((showLine & 0x08) != 0) { // Mask 8 (0000 1000) to show SD line
PlotD.Set(Stochastics(StocD, StocK, StocSmooth)[0]);
}
Note: One "&" or one "|" does bit manipulation. Two "&&" or "||" does logic comparisions.

enjoy Dave.
Disclaimer: Using Enumerated datatypes as Indicators is not supported by Ninja. This means it might break in a future release &/or might not work with other parts of Ninja. Test it well & remember to regresion test it with each new Ninja release.
That said, enums are a core part of the C# language. Its hard to see how they could bite you.

[NinjaTrader_JoshP]

David,

Thank you for this thorough writeup. We appreciate you taking the time and sharing with the community.

[aslane]

Nice write up.

One thing to keep in mind though is to not pollute the name space with your type names. Your public enum MAType effectively becomes a global name which is fine, but can cause some name collisions. Best to use a unique name by having a prefix.