name: metalama-2026.0 description: Complete Metalama documentation for aspect-oriented programming in C#. Use when writing aspects, templates, fabrics, or meta-programming code with Metalama.

Metalama Documentation Skill

This skill contains the complete Metalama documentation including conceptual guides, API reference, and sample code.

This skill pertains to Metalama 2026.0.

Directory Structure

Finding Information

1. Search the index: Use grep with -B3 to search index.yml for keywords (each entry has: name, path, summary, keywords - so -B3 captures the path):

   grep -i -B3 "caching" index.yml
   grep -i -B3 "BuildAspect" index.yml
   

2. Browse by topic: Navigate the content/ directory structure.
3. API lookup: Use grep on api/.manifest to find API YML files by type or member name:

   grep -i "OverrideMethodAspect" api/.manifest
   

Key Entry Points

Common Patterns

Base Classes

Template Fundamentals

[!IMPORTANT] T# templates look like C# but have different semantics. Code that works in normal C# may not work identically in a template. Always read the full template documentation at content/conceptual/aspects/templates/ before writing template code.

public override dynamic? OverrideMethod()
{
    // Pre-logic
    try
    {
        return meta.Proceed();  // Calls original method
    }
    finally
    {
        // Post-logic (always runs)
    }
}

• dynamic? handles any return type (void returns null)
• meta.Proceed() auto-transforms to await for async targets
• Use meta.Target.* to access compile-time information about the target declaration
• To debug templates, use meta.DebugBreak() (not Debugger.Break())

Debugging Quick Reference

Debugging compile-time code (aspects, fabrics, templates):

1. Add Debugger.Break() in BuildAspect/fabrics, or meta.DebugBreak() in templates
2. Build with: dotnet build -p:MetalamaDebugCompiler=True -p:MetalamaConcurrentBuildEnabled=False
3. Attach debugger when prompted, then set breakpoints in transformed code (obj/.../metalama/)

Debugging run-time code (transformed output):

1. Create a LamaDebug build configuration in Visual Studio
2. Use F11 to step into code, or add Debugger.Break()
3. Set breakpoints in transformed files under obj/<Config>/<TFM>/metalama/

Common Pitfalls

Sample Code Conventions

• Name.cs - Target code receiving the aspect
• Name.Aspect.cs - Aspect implementation
• Name.t.cs - Transformed output (what the compiler generates)
• Name.Dependency.cs - Referenced project code for multi-project examples

Metalama Markdown Directives

The documentation uses custom [!metalama-*] directives to include code samples. These are processed at build time to generate HTML, but in the skill files you see the raw directives.

Reading Directive References

When you see a directive in a Markdown file, extract the file path and read the referenced file directly.

Path Resolution

• ~/ resolves to the SKILLS.md directory
• Example: ~/code/Metalama.Documentation.SampleCode.AspectFramework/GettingStarted/GettingStarted.cs → Read code/Metalama.Documentation.SampleCode.AspectFramework/GettingStarted/GettingStarted.cs

How to Read Referenced Code

When you encounter a directive like [!metalama-file ~/code/Project/File.cs]:

1. Read the main file: code/Project/File.cs
2. Check for related files (same name, different suffix):
   • File.Aspect.cs - Aspect implementation
   • File.t.cs - Transformed output
   • File.Fabric.cs - Fabric code

Markers: If you see marker="NAME", look for code between // [<snippet NAME>] and // [<endsnippet NAME>] in the file.

API Reference

The api/ directory contains DocFx-generated YML files for all public APIs.

Finding API Documentation

Use api/.manifest - a JSON index mapping all UIDs (types, members, overloads) to their YML files.

1. Search the manifest for the type or member name:

   "Metalama.Framework.Aspects.OverrideMethodAspect": "Metalama.Framework.Aspects.OverrideMethodAspect.yml"
   "Metalama.Framework.Aspects.OverrideMethodAspect.OverrideMethod": "Metalama.Framework.Aspects.OverrideMethodAspect.yml"
   "Metalama.Framework.Code.IMethod": "Metalama.Framework.Code.IMethod.yml"
   

2. Read the corresponding YML file to get full documentation.

3. Naming conventions:

   • Types: Namespace.TypeName.yml
   • Generic types: backtick becomes dash, e.g., IAspectBuilder<T> → Metalama.Framework.Aspects.IAspectBuilder-1.yml
   • All members of a type are in the same YML file as the type

YML File Structure

Each type's YML file contains all members of that type in a single file:

items:
- uid: Namespace.TypeName           # Type definition
  commentId: T:Namespace.TypeName
  type: Class|Interface|Enum|...
  summary: Type description
  remarks: Detailed explanation
  syntax:
    content: public class TypeName : BaseClass
  children:                         # List of member UIDs
  - Namespace.TypeName.Method1
  - Namespace.TypeName.Property1

- uid: Namespace.TypeName.Method1   # Member definition
  commentId: M:Namespace.TypeName.Method1
  type: Method|Property|Field|...
  summary: Member description
  syntax:
    content: public void Method1()
  parameters: [...]                 # For methods
  return: { type: ..., description: ... }

Key Namespaces

Linking to Documentation

When referencing documentation articles, provide links to the live documentation at https://doc.metalama.net.

URL format: https://doc.metalama.net/<path> where <path> is derived from the file path under content/:

• Remove content/ prefix
• Remove .md suffix
• For index files where the filename matches the parent folder (e.g., path/leaf/leaf.md), use just path/leaf

Examples:

External Resources

• Live documentation: https://doc.metalama.net
• Source repository: https://github.com/metalama/Metalama
• Samples repository: https://github.com/metalama/Metalama.Samples