البُناة الساكنة

ما هو المُنشئ الساكن؟

using System;

class App
{
    public static string Version;

    static App()
    {
        Version = "1.0.0";
        Console.WriteLine("Static constructor ran");
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(App.Version);
    }
}

قواعد الصياغة

using System;

class Config
{
    public static int MaxUsers;

    static Config()
    {
        MaxUsers = 100;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine("Max: " + Config.MaxUsers);
    }
}

يُنفَّذ مرة واحدة تمامًا

using System;

class Counter
{
    public static int Instances;

    static Counter()
    {
        Console.WriteLine("Initializing static state");
        Instances = 0;
    }

    public Counter() { Instances++; }
}

class Program
{
    static void Main()
    {
        new Counter();
        new Counter();
        Console.WriteLine("Instances: " + Counter.Instances);
    }
}

متى يُفعَّل؟

using System;

class Lazy
{
    public static string Data;

    static Lazy()
    {
        Console.WriteLine("Triggered now");
        Data = "ready";
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine("Before access");
        Console.WriteLine(Lazy.Data);
    }
}

تهيئة البيانات الساكنة المعقدة

using System;
using System.Collections.Generic;

class Lookup
{
    public static Dictionary<int, string> Table;

    static Lookup()
    {
        Table = new Dictionary<int, string>();
        for (int i = 1; i <= 3; i++)
            Table[i] = "Item" + i;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Lookup.Table[2]);
    }
}

المُنشئ الساكن مقابل مُهيِّئ الحقل

using System;

class Settings
{
    public static int Simple = 10;        // inline initializer
    public static int Computed;            // needs logic

    static Settings()
    {
        Computed = Simple * Simple;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Settings.Simple + ", " + Settings.Computed);
    }
}

لا يُسمح بالمعلمات

using System;

class Clock
{
    public static int StartHour;

    static Clock()
    {
        StartHour = 9;
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine("Start: " + Clock.StartHour);
    }
}

دمج المُنشئات الساكنة ومُنشئات المثيلات

using System;

class Game
{
    public static string Title;
    public int Score;

    static Game()
    {
        Title = "Coddy Quest";
    }

    public Game(int score)
    {
        Score = score;
    }
}

class Program
{
    static void Main()
    {
        var g = new Game(50);
        Console.WriteLine(Game.Title + " score " + g.Score);
    }
}

ضمان الترتيب

using System;

class Service
{
    public static string Endpoint;

    static Service()
    {
        Endpoint = "https://api.example.com";
    }

    public Service()
    {
        Console.WriteLine("Using " + Endpoint);
    }
}

class Program
{
    static void Main()
    {
        new Service();
    }
}

استخدموه باعتدال

using System;

class Cache
{
    public static int[] Data;

    static Cache()
    {
        Data = new int[] { 2, 4, 6, 8 };
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Cache.Data[3]);
    }
}

تجميع المفاهيم

using System;
using System.Collections.Generic;

class Currency
{
    public static Dictionary<string, string> Symbols;

    static Currency()
    {
        Symbols = new Dictionary<string, string>
        {
            ["USD"] = "$",
            ["EUR"] = "E",
            ["JPY"] = "Y"
        };
    }
}

class Program
{
    static void Main()
    {
        Console.WriteLine("USD symbol: " + Currency.Symbols["USD"]);
    }
}

تحقق سريع

مراجعة

using System;

class Demo
{
    public static int Value;
    static Demo() { Value = 42; }
}

class Program
{
    static void Main()
    {
        Console.WriteLine(Demo.Value);
    }
}