Indicator catalog development

File structure

• Catalog: src/{category}/{Indicator}/{Indicator}.Catalog.cs
• Location: Same directory as {Indicator}.Models.cs

Builder pattern

public static partial class Ema
{
    /// <summary>
    /// EMA Common Base Listing
    /// </summary>
    internal static readonly IndicatorListing CommonListing =
        new CatalogListingBuilder()
            .WithName("Exponential Moving Average")
            .WithId("EMA")
            .WithCategory(Category.MovingAverage)
            .AddParameter<int>("lookbackPeriods", "Lookback Period",
                description: "Number of periods for the EMA calculation",
                isRequired: true, defaultValue: 20, minimum: 2, maximum: 250)
            .AddResult("Ema", "EMA", ResultType.Default, isReusable: true)
            .Build();

    /// <summary>
    /// EMA Series Listing
    /// </summary>
    internal static readonly IndicatorListing SeriesListing =
        new CatalogListingBuilder(CommonListing)
            .WithStyle(Style.Series)
            .WithMethodName("ToEma")
            .Build();

    /// <summary>
    /// EMA Stream Listing
    /// </summary>
    internal static readonly IndicatorListing StreamListing =
        new CatalogListingBuilder(CommonListing)
            .WithStyle(Style.Stream)
            .WithMethodName("ToEmaHub")
            .Build();

    /// <summary>
    /// EMA Buffer Listing
    /// </summary>
    internal static readonly IndicatorListing BufferListing =
        new CatalogListingBuilder(CommonListing)
            .WithStyle(Style.Buffer)
            .WithMethodName("ToEmaList")
            .Build();
}

Method naming conventions

Style	Pattern	Example
Series	To{IndicatorName}	ToEma
Stream	To{IndicatorName}Hub	ToEmaHub
Buffer	To{IndicatorName}List	ToEmaList

Critical: .WithMethodName() must be in style-specific listings, NOT in CommonListing.

Required parameter patterns

• Use AddParameter<T>() for basic types (int, double, bool)
• Use AddEnumParameter<T>() for enum types
• Use AddDateParameter() for DateTime parameters
• Use AddSeriesParameter() for IReadOnlyList<T> where T : IReusable
• MUST set minimum and maximum for all numeric parameters

Required result patterns

• dataName MUST match property name in Models file exactly
• Set isReusable: true ONLY for property mapping to IReusable.Value
• ISeries models: ALL results MUST have isReusable: false
• Exactly ONE result with isReusable: true per IReusable indicator

Categories

Category	Examples
MovingAverage	EMA, SMA, HMA, TEMA
Oscillator	RSI, Stochastic, MACD
PriceChannel	Bollinger Bands, Keltner
Trend	ADX, Aroon, Parabolic SAR
Volume	OBV, Chaikin Money Flow
Volatility	ATR, Standard Deviation

Registration

Add to src/_common/Catalog/Catalog.Listings.cs in PopulateCatalog():

_catalog.Add(Ema.SeriesListing);
_catalog.Add(Ema.StreamListing);
_catalog.Add(Ema.BufferListing);

Register in alphabetical order by indicator name.

Testing

Create tests/indicators/{folder}/{Indicator}/{Indicator}.Catalog.Tests.cs:

[TestClass]
public class EmaCatalogTests : TestBase
{
    [TestMethod]
    public void EmaSeriesListing()
    {
        var listing = Ema.SeriesListing;
        listing.Name.Should().Be("Exponential Moving Average");
        listing.Style.Should().Be(Style.Series);
        listing.MethodName.Should().Be("ToEma");
    }
}

Prohibited patterns

• ❌ .WithMethodName() in CommonListing (MUST be in style-specific listings)
• ❌ Wrong indicator method name (breaks extension method discovery)
• ❌ isReusable: true for ISeries models (violates interface contract)
• ❌ Multiple isReusable: true results (ambiguous Value mapping)

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Last updated: December 31, 2025