Soenneker.Gen.Reflection

Compile-time reflection for .NET

Installation

dotnet add package Soenneker.Gen.Reflection

Features

GetTypeGen Extension Method

The GetTypeGen() extension method provides compile-time generated type information without runtime reflection overhead. This source generator analyzes your code and generates highly optimized non-reflection based code for type introspection.

Basic Usage

using Soenneker.Gen.Reflection;

// Get type information from an instance
string text = "Hello World";
var typeInfo = text.GetTypeGen();

Console.WriteLine($"Type: {typeInfo.Name}");           // "String"
Console.WriteLine($"Is Value Type: {typeInfo.IsValueType}"); // false
Console.WriteLine($"Is Reference Type: {typeInfo.IsReferenceType}"); // true

Generic Method Usage

// Get type information using generic method
var listTypeInfo = GetTypeGen<List<string>>();
Console.WriteLine($"Type: {listTypeInfo.Name}"); // "List`1"
Console.WriteLine($"Is Generic: {listTypeInfo.IsGenericType}"); // true
Console.WriteLine($"Generic Args: {listTypeInfo.GenericTypeArguments.Length}"); // 1

Property and Field Access

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
    private readonly string _id = Guid.NewGuid().ToString();
}

var person = new Person { Name = "John", Age = 30 };
var personTypeInfo = person.GetTypeGen();

// Access properties
var nameProperty = personTypeInfo.GetProperty("Name");
if (nameProperty.HasValue)
{
    Console.WriteLine($"Property: {nameProperty.Value.Name}");
    Console.WriteLine($"Type: {nameProperty.Value.PropertyType.Name}");
    Console.WriteLine($"Value: {nameProperty.Value.GetValue(person)}");
}

// Access fields
var fields = personTypeInfo.Fields;
foreach (var field in fields)
{
    Console.WriteLine($"Field: {field.Name} ({field.FieldType.Name})");
}

Method Information

var personTypeInfo = person.GetTypeGen();
var toStringMethod = personTypeInfo.GetMethod("ToString");

if (toStringMethod.HasValue)
{
    Console.WriteLine($"Method: {toStringMethod.Value.Name}");
    Console.WriteLine($"Return Type: {toStringMethod.Value.ReturnType.Name}");
    Console.WriteLine($"Parameters: {toStringMethod.Value.ParameterTypes.Length}");
    
    // Invoke the method
    var result = toStringMethod.Value.Invoke(person, null);
    Console.WriteLine($"Result: {result}");
}

Nullable Types

int? nullableInt = 42;
var nullableTypeInfo = nullableInt.GetTypeGen();

Console.WriteLine($"Type: {nullableTypeInfo.Name}"); // "Nullable`1"
Console.WriteLine($"Is Nullable: {nullableTypeInfo.IsNullable}"); // true

if (nullableTypeInfo.UnderlyingType.HasValue)
{
    Console.WriteLine($"Underlying: {nullableTypeInfo.UnderlyingType.Value.Name}"); // "Int32"
}

Razor/Blazor Support

The source generator also works in Razor components:

@{
    string text = "Hello Blazor";
    var typeInfo = text.GetTypeGen();
}

<p>Type: @typeInfo.Name</p>
<p>Is Reference Type: @typeInfo.IsReferenceType</p>

Generated Code

The source generator creates optimized code at compile time. For example, when you call text.GetTypeGen(), the generator creates:

// Generated code (simplified)
public static partial class StringTypeInfo
{
    public static string Name => "String";
    public static string FullName => "System.String";
    public static bool IsValueType => false;
    public static bool IsReferenceType => true;
    public static bool IsGenericType => false;
    public static bool IsNullable => false;
    // ... more properties
}

Performance Benefits

• Zero Runtime Reflection: All type information is generated at compile time
• Optimized Code: Direct property access instead of reflection calls
• Type Safety: Compile-time type checking and IntelliSense support
• Minimal Memory Overhead: No reflection metadata loaded at runtime