Namespace: System.Reflection.Metadata

Namespace: System.Reflection.Metadata

Assembly: System.Reflection.Metadata.dll

This namespace provides types for accessing and manipulating metadata of .NET assemblies. It's a low-level API designed for scenarios like assembly analysis, code generation, and diagnostics tools.

Summary

The System.Reflection.Metadata namespace offers a powerful and efficient way to read and write the metadata structures of .NET assemblies, including types, methods, fields, properties, events, and their associated attributes and signatures. Unlike higher-level reflection APIs, this namespace operates directly on the Portable Executable (PE) file format, providing granular control and performance benefits.

Key Concepts

  • MetadataReader: The primary entry point for reading metadata from an assembly.
  • MetadataBuilder: Used to create and modify metadata.
  • Entity Handle: Represents a reference to a metadata entity (e.g., TypeDefinitionHandle, MethodDefinitionHandle).
  • RowId: A unique identifier for a row within a metadata table.
  • String, GUID, Blob: Structures for accessing string literals, GUIDs, and binary blobs stored in the metadata.

Classes

Class Description
MetadataReader Represents a reader for the metadata of a .NET assembly.
MetadataBuilder Represents a builder for .NET assembly metadata.
EntityHandle Represents a handle to a metadata entity.
TypeDefinition Represents a type definition in the metadata.
MethodDefinition Represents a method definition in the metadata.
Parameter Represents a parameter of a method.
FieldDefinition Represents a field definition.
PropertyDefinition Represents a property definition.
EventDefinition Represents an event definition.

Example Usage

The following C# code snippet demonstrates how to read type names from an assembly using MetadataReader:


using System;
using System.Reflection.Metadata;
using System.Reflection.PortableExecutable;
using System.IO;

// Load the assembly metadata
using (var stream = File.OpenRead("YourAssembly.dll"))
using (var peReader = new PEReader(stream))
{
    MetadataReader metadataReader = peReader.GetMetadataReader();

    Console.WriteLine("Types in the assembly:");
    foreach (var typeHandle in metadataReader.TypeDefinitions)
    {
        TypeDefinition typeDefinition = metadataReader.GetTypeDefinition(typeHandle);
        string typeName = metadataReader.GetString(metadataReader.GetTypeDefinition(typeHandle).Name);
        Console.WriteLine($"- {typeName}");
    }
}

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