Source Generators

ALPHA RELEASE

Switchboard is currently in preview (v0.1.0-preview.17). APIs may change between releases.

Switchboard uses C# source generators to automatically create flow implementations from your attribute-decorated classes. This eliminates boilerplate code and ensures consistency across your contact center infrastructure.

What Are Source Generators?

Source generators are compile-time code generators that analyze your code and produce additional C# source files. They run as part of the compiler pipeline, so generated code is available immediately with full IntelliSense support.

Your Code (Attributes)
        ↓
Roslyn Compiler
        ↓
Source Generator Analysis
        ↓
Generated Code (automatic)
        ↓
Final Compilation

How Switchboard Uses Generators

Input: Your Attributed Class

[ContactFlow("WelcomeFlow")]
public partial class WelcomeFlow : FlowDefinitionBase
{
    [Message("Welcome to our contact center")]
    public partial void Welcome();

    [TransferToQueue("GeneralSupport")]
    public partial void Transfer();
}

Output: Generated Implementation

The source generator automatically creates:

// WelcomeFlow.g.cs (generated)
public partial class WelcomeFlow
{
    private readonly List<IAction> _actions = new();

    public partial void Welcome()
    {
        _actions.Add(new MessageAction
        {
            Identifier = "Welcome-001",
            Text = "Welcome to our contact center",
            Transitions = new Transitions { NextAction = "Transfer-001" }
        });
    }

    public partial void Transfer()
    {
        _actions.Add(new TransferToQueueAction
        {
            Identifier = "Transfer-001",
            QueueName = "GeneralSupport"
        });
    }

    public override CfnContactFlow BuildCdkConstruct(Construct scope)
    {
        // Execute methods to populate actions
        Welcome();
        Transfer();

        return new CfnContactFlow(scope, "WelcomeFlow", new CfnContactFlowProps
        {
            Name = "WelcomeFlow",
            Type = "CONTACT_FLOW",
            Content = SerializeActions(_actions),
            InstanceArn = GetInstanceArn(scope)
        });
    }
}

Built-In Generators

Switchboard includes several source generators:

1. FlowDefinitionGenerator

Generates flow implementations from [ContactFlow] attributes.

See: Reference: Source Generators for complete details.

2. DynamoDbSchemaGenerator

Generates DynamoDB table definitions from configuration models.

3. LambdaHandlerGenerator

Creates Lambda function handlers for dynamic configuration.

Viewing Generated Code

Visual Studio

1. Expand project in Solution Explorer
2. Navigate to Dependencies → Analyzers → NickSoftware.Switchboard.SourceGenerators
3. View generated .g.cs files

Rider

1. Right-click project → Navigate To → Generated Files
2. Browse generated source files

Command Line

Generated files are in:

obj/Debug/net10.0/generated/NickSoftware.Switchboard.SourceGenerators/

Benefits

1. ✅ Less boilerplate - Write declarations, get implementations
2. ✅ Compile-time generation - No runtime overhead
3. ✅ Type safety - Generated code is strongly typed
4. ✅ IntelliSense support - Full IDE integration
5. ✅ Consistency - Same patterns across all flows

Next Steps

• Reference: Source Generators - Complete generator documentation
• Roslyn Analyzers - Compile-time validation
• Attribute-Based Flows - Using attributes
• Architecture - How generators fit in

Related Resources

• Attributes - Declarative configuration
• Flow Basics - Building flows