Type parameters naming (T, TKey, TValue)

Context: By convention, type parameters are named with a prefix T (for Type). For a single parameter, use T. For multiple parameters, use descriptive names like TKey, TValue, TInput, TOutput. This improves code readability.

Usage Example

using System;
using System.Collections.Generic;

// Convention: T for a single type
public class Transformer<T>
{
    public T Transform(T input)
    {
        return input;
    }
}

// Convention: TKey and TValue for a dictionary
public class SimpleDictionary<TKey, TValue>
{
    private Dictionary<TKey, TValue> _dictionary = new Dictionary<TKey, TValue>();

    public void Add(TKey key, TValue value)
    {
        _dictionary.Add(key, value);
    }

    public TValue Get(TKey key)
    {
        return _dictionary[key];
    }
}

class Program
{
    static void Main()
    {
        var dict = new SimpleDictionary<string, int>();
        dict.Add("age", 30);
        Console.WriteLine(dict.Get("age"));
    }
}

Output console

dotnet run
30

Important notes

• T is the most common name for a single type parameter.
• TKey and TValue are used for key-value collections.
• Avoid names like T1, T2 except for trivial cases.

Real-world usage example

Dictionary<TKey, TValue> – Uses exactly this convention. List<T> uses T.
See .NET docs on naming conventions.

Related sections

• 11.1.1 Syntax
• 11.2 Generic methods