Delegates and Lambdas

Method Groups

A method name can be assigned to a compatible delegate variable.

method group A method group is a method name used where a delegate is expected.

Method Groups

price
MethodGroups.cs
Replay: real traced execution (multi-file project)
using System;

class Program
{
    static int AddTax(int cents)
    {
        return cents + 5;
    }

    static void Main()
    {
        int price = 40;
        Func<int, int> calculator = AddTax;
        int total = calculator(price);

        Console.WriteLine($"price={price}");
        Console.WriteLine($"total={total}");
    }
}

using System;

class Program
{
    static int AddTax(int cents)
    {
        return cents + 5;
    }

    static void Main()
    {
        int price = 20;
        Func<int, int> calculator = AddTax;
        int total = calculator(price);

        Console.WriteLine($"price={price}");
        Console.WriteLine($"total={total}");
    }
}

using System;

class Program
{
    static int AddTax(int cents)
    {
        return cents + 5;
    }

    static void Main()
    {
        int price = 75;
        Func<int, int> calculator = AddTax;
        int total = calculator(price);

        Console.WriteLine($"price={price}");
        Console.WriteLine($"total={total}");
    }
}

  1. price ← 40, calculator ← System.Func`2[System.Int32,System.Int32]

    10static void Main()11{12    int price→ 40 = 40; //@price=20, 7513    Func<int, int> calculator→ System.Func`2[System.Int32,System.Int32] = AddTax;14    int total = calculator(price40);

  2. static int AddTax(int cents)

    4{5    static int AddTax(int cents40)6    {7        return cents40 + 5;8    }

  3. total ← 45

    13    Func<int, int> calculator = AddTax;14    int total→ 45 = calculator(price40);1516    Console.WriteLine($"price={price40}");17    Console.WriteLine($"total={total45}");18}
    outputprice=40
total=45

  1. price ← 20, calculator ← System.Func`2[System.Int32,System.Int32]

    10static void Main()11{12    int price→ 20 = 20;13    Func<int, int> calculator→ System.Func`2[System.Int32,System.Int32] = AddTax;14    int total = calculator(price20);

  2. static int AddTax(int cents)

    4{5    static int AddTax(int cents20)6    {7        return cents20 + 5;8    }

  3. total ← 25

    13    Func<int, int> calculator = AddTax;14    int total→ 25 = calculator(price20);1516    Console.WriteLine($"price={price20}");17    Console.WriteLine($"total={total25}");18}
    outputprice=20
total=25

  1. price ← 75, calculator ← System.Func`2[System.Int32,System.Int32]

    10static void Main()11{12    int price→ 75 = 75;13    Func<int, int> calculator→ System.Func`2[System.Int32,System.Int32] = AddTax;14    int total = calculator(price75);

  2. static int AddTax(int cents)

    4{5    static int AddTax(int cents75)6    {7        return cents75 + 5;8    }

  3. total ← 80

    13    Func<int, int> calculator = AddTax;14    int total→ 80 = calculator(price75);1516    Console.WriteLine($"price={price75}");17    Console.WriteLine($"total={total80}");18}
    outputprice=75
total=80