TypeParamAttribute

The TypeParamAttribute class provides metadata about type parameters in generic type definitions. It is primarily used by tools and documentation generators to describe generic constraints and relationships.

Namespace

System.Runtime.CompilerServices

Assembly

System.Runtime.dll

Inheritance

System.Attribute → TypeParamAttribute

Syntax

public sealed class TypeParamAttribute : Attribute
{
    public TypeParamAttribute(string name);
    public string Name { get; }
    public string? Description { get; set; }
    public Type[]? Constraints { get; set; }
}

Members

Member	Signature	Description
Constructor	`TypeParamAttribute(string name)`	Initializes a new instance with the required name of the type parameter.
Property	`string Name { get; }`	Gets the name of the type parameter.
Property	`string? Description { get; set; }`	Optional human‑readable description.
Property	`Type[]? Constraints { get; set; }`	Array of constraint types applied to the type parameter.

Usage

Applied to generic type declarations to provide additional information for documentation tools.

[TypeParam("T", Description = "The item type.", Constraints = new[] { typeof(IDisposable) })]
public class Repository<T> where T : IDisposable
{
    // Implementation...
}

Examples

Example 1 – Basic Documentation

using System;
using System.Runtime.CompilerServices;

[AttributeUsage(AttributeTargets.GenericParameter, Inherited = false)]
public sealed class TypeParamAttribute : Attribute
{
    public TypeParamAttribute(string name) => Name = name;
    public string Name { get; }
    public string? Description { get; set; }
    public Type[]? Constraints { get; set; }
}

[TypeParam("T", Description = "The data type stored in the collection.")]
public class MyCollection<T>
{
    // …
}

Example 2 – Multiple Parameters

[TypeParam("TKey", Description = "Key type.", Constraints = new[] { typeof(IComparable) })]
[TypeParam("TValue", Description = "Value type.")]
public class PairDictionary<TKey, TValue> where TKey : IComparable
{
    // …
}