Source Generators

Termina uses C# source generators to eliminate boilerplate code while maintaining AOT compatibility.

Why Source Generators?

Source generators provide:

1. No Reflection - Code is generated at compile time, not runtime
2. AOT Compatible - Works with Native AOT publishing
3. IDE Support - Generated code appears in IntelliSense
4. Debuggable - You can step into generated code

Termina uses source generators for route parameter injection via the [FromRoute] attribute.

The [FromRoute] Generator

What You Write

public partial class DetailViewModel : ReactiveViewModel
{
    [FromRoute] private int _id;
}

What Gets Generated

// DetailViewModel.g.cs (generated)
partial class DetailViewModel
{
    public int Id { get; private set; }

    internal void ApplyRouteParameters(IDictionary<string, object> parameters)
    {
        if (parameters.TryGetValue("id", out var idValue))
        {
            Id = Convert.ToInt32(idValue);
        }
    }
}

WARNING

Your ViewModel class must be partial when using [FromRoute] for the source generator to work.

Viewing Generated Code

To see the generated code in your IDE, add to your project file:

<PropertyGroup>
  <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)Generated</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

Generated files appear in obj/Generated/.

Key Requirements

Partial Classes (for [FromRoute])

Your ViewModel class must be partial when using [FromRoute]:

// ✓ Correct
public partial class MyViewModel : ReactiveViewModel
{
    [FromRoute] private int _id;
}

// ✗ Won't work - missing partial
public class MyViewModel : ReactiveViewModel
{
    [FromRoute] private int _id;
}

TIP

If your ViewModel doesn't use [FromRoute], it does not need to be partial. Reactive state is managed with ReactiveProperty<T> which doesn't require source generation.

Field Naming

[FromRoute] fields must start with _ and use camelCase:

// ✓ Correct
[FromRoute] private int _id;          // → Id
[FromRoute] private string _userName; // → UserName

// ✗ Won't work correctly
[FromRoute] private int id;           // No underscore
[FromRoute] private int Id;           // PascalCase

Benefits for AOT

Traditional frameworks use reflection to:

• Find properties at runtime
• Create bindings dynamically
• Invoke property changed notifications

Termina's approach:

• [FromRoute] generates route parameter binding at compile time
• ReactiveProperty<T> provides observable state without reflection
• Full support for PublishAot=true

# Works because no reflection is needed
dotnet publish -c Release -r win-x64 --self-contained /p:PublishAot=true