Nullable and Pattern Matching

Property Patterns

A property pattern checks selected properties on an object.

property pattern A property pattern matches an object by reading named properties.

Property Patterns

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

class Order
{
    public string Status { get; }
    public int Total { get; }

    public Order(string status, int total)
    {
        Status = status;
        Total = total;
    }

    public override string ToString()
    {
        return Status + ":" + Total;
    }
}

class Program
{
    static void Main()
    {
        int total = 120;
        Order order = new Order("paid", total);
        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

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

using System;

class Order
{
    public string Status { get; }
    public int Total { get; }

    public Order(string status, int total)
    {
        Status = status;
        Total = total;
    }

    public override string ToString()
    {
        return Status + ":" + Total;
    }
}

class Program
{
    static void Main()
    {
        int total = 40;
        Order order = new Order("paid", total);
        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

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

using System;

class Order
{
    public string Status { get; }
    public int Total { get; }

    public Order(string status, int total)
    {
        Status = status;
        Total = total;
    }

    public override string ToString()
    {
        return Status + ":" + Total;
    }
}

class Program
{
    static void Main()
    {
        int total = 150;
        Order order = new Order("paid", total);
        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

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

  1. total ← 120

    21{22    static void Main()23    {24        int total→ 120 = 120; //@total=40, 15025        Order order = new Order("paid", total);26        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

  2. public Order(string status, int total)

    8public Order(string statuspaid, int total120)9{10    Status = statuspaid;11    Total = total120;12}

  3. order ← paid:120, result ← priority

    24    int total = 120; //@total=40, 15025    Order order→ paid:120 = new Order("paid", total);26    string result→ priority = orderpaid:120 is { Status: "paid", Total: >= 100 } ? "priority" : "standard";2728    Console.WriteLine($"total={total120}");29    Console.WriteLine($"result={resultpriority}");30}
    outputtotal=120
result=priority

  1. total ← 40

    21{22    static void Main()23    {24        int total→ 40 = 40;25        Order order = new Order("paid", total);26        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

  2. public Order(string status, int total)

    8public Order(string statuspaid, int total40)9{10    Status = statuspaid;11    Total = total40;12}

  3. order ← paid:40, result ← standard

    24    int total = 40;25    Order order→ paid:40 = new Order("paid", total);26    string result→ standard = orderpaid:40 is { Status: "paid", Total: >= 100 } ? "priority" : "standard";2728    Console.WriteLine($"total={total40}");29    Console.WriteLine($"result={resultstandard}");30}
    outputtotal=40
result=standard

  1. total ← 150

    21{22    static void Main()23    {24        int total→ 150 = 150;25        Order order = new Order("paid", total);26        string result = order is { Status: "paid", Total: >= 100 } ? "priority" : "standard";

  2. public Order(string status, int total)

    8public Order(string statuspaid, int total150)9{10    Status = statuspaid;11    Total = total150;12}

  3. order ← paid:150, result ← priority

    24    int total = 150;25    Order order→ paid:150 = new Order("paid", total);26    string result→ priority = orderpaid:150 is { Status: "paid", Total: >= 100 } ? "priority" : "standard";2728    Console.WriteLine($"total={total150}");29    Console.WriteLine($"result={resultpriority}");30}
    outputtotal=150
result=priority