我正在尋找一種方法來允許另一個類通過調用該類的方法向我的 Action 委托添加方法，而不是在第一個類上調用 Action。這就是我需要的：class Program{ static void Main(string[] args) { Action Execute = delegate { }; ProgramTest prog = new ProgramTest(ref Execute); prog.AddMethod(); Execute(); }}class ProgramTest{ public Action execute; public ProgramTest(ref Action action) { execute = action; } public void AddMethod() { execute += Print; } public void Print() { Console.WriteLine("test"); Console.ReadLine(); }}但是，當我調用 Execute() 時，什么也沒有發生。我怎樣才能讓它工作？
4 回答
慕容3067478
TA貢獻1773條經驗 獲得超3個贊
另一種選擇是將（不可變的）委托放在可變容器中。
public class ActionContainer
{
public Action Action { get; set; } = () => { };
}
class Program
{
static void Main(string[] args)
{
ActionContainer execute = new ActionContainer();
ProgramTest prog = new ProgramTest(execute);
prog.AddMethod();
execute.Action();
}
}
class ProgramTest
{
public ActionContainer execute;
public ProgramTest(ActionContainer action)
{
execute = action;
}
public void AddMethod()
{
execute.Action += Print;
}
public void Print()
{
Console.WriteLine("test");
Console.ReadLine();
}
}
精慕HU
TA貢獻1845條經驗 獲得超8個贊
你想要的是這樣的：
class Program
{
static void Main(string[] args)
{
Action Execute = delegate { };
ProgramTest prog = new ProgramTest(h => Execute += h);
prog.AddMethod();
Execute();
}
}
class ProgramTest
{
public Action<Action> execute;
public ProgramTest(Action<Action> action)
{
execute = action;
}
public void AddMethod()
{
execute(Print);
}
public void Print()
{
Console.WriteLine("test");
Console.ReadLine();
}
}
打印test到控制臺。
這是這個模式的一個稍微好一點的版本：
class Program
{
static void Main(string[] args)
{
Action Execute = delegate { };
ProgramTest prog = new ProgramTest(h => Execute += h, h => Execute -= h);
var subscription = prog.AddMethod();
Execute();
subscription.Dispose();
}
}
class ProgramTest
{
public Action<Action> _attach;
public Action<Action> _detach;
public ProgramTest(Action<Action> attach, Action<Action> detach)
{
_attach = attach;
_detach = detach;
}
public IDisposable AddMethod()
{
_attach(Print);
return Disposable.Create(() => _detach(Print));
}
public void Print()
{
Console.WriteLine("test");
Console.ReadLine();
}
}
public sealed class Disposable : IDisposable
{
public static IDisposable Create(Action action)
=> new Disposable(action);
private readonly Action _action;
private int _disposed;
private Disposable(Action action)
{
_action = action;
}
public void Dispose()
{
if (Interlocked.Exchange(ref _disposed, 1) == 0)
{
_action();
}
}
}
我什至會更進一步并定義一個MetaAction- 您可以隨意傳遞它并向其添加方法。
class Program
{
static void Main(string[] args)
{
Action Execute = delegate { };
MetaAction meta = MetaAction.Create(h => Execute += h, h => Execute -= h);
var prog = new ProgramTest(meta);
var subscription = prog.AddMethod();
Execute();
subscription.Dispose();
}
}
public class MetaAction
{
public static MetaAction Create(Action<Action> attach, Action<Action> detach)
=> new MetaAction(attach, detach);
public Action<Action> _attach;
public Action<Action> _detach;
private MetaAction(Action<Action> attach, Action<Action> detach)
{
_attach = attach;
_detach = detach;
}
public IDisposable Subscribe(Action action)
{
_attach(action);
return Disposable.Create(() => _detach(action));
}
}
public class ProgramTest
{
public MetaAction _meta;
public ProgramTest(MetaAction meta)
{
_meta = meta;
}
public IDisposable AddMethod()
{
return _meta.Subscribe(Print);
}
public void Print()
{
Console.WriteLine("test");
Console.ReadLine();
}
}
public sealed class Disposable : IDisposable
{
public static IDisposable Create(Action action)
=> new Disposable(action);
private readonly Action _action;
private int _disposed;
private Disposable(Action action)
{
_action = action;
}
public void Dispose()
{
if (Interlocked.Exchange(ref _disposed, 1) == 0)
{
_action();
}
}
}
慕標5832272
TA貢獻1966條經驗 獲得超4個贊
您可以通過調用 prog.Execute 而不是 Execute 來使其工作，就像下面的代碼一樣。
class Program
{
static void Main(string[] args)
{
Action Execute = delegate { };
ProgramTest prog = new ProgramTest(ref Execute);
prog.AddMethod();
prog.execute();
}
}
或者您需要將 Print 方法分配給 main 方法執行委托，如下所示
class Program
{
static void Main(string[] args)
{
Action Execute = delegate { };
ProgramTest prog = new ProgramTest(ref Execute);
Execute += prog.Print;
prog.AddMethod();
Execute();
}
}
qq_花開花謝_0
TA貢獻1835條經驗 獲得超7個贊
您Program可能會公開一個事件，您的其他類可能會向該事件注冊另一個處理程序：
class Program
{
public static event Action MyEvent;
static void Main(string[] args)
{
ProgramTest prog = new ProgramTest();
prog.AddMethod();
// raise the event and invoke the registered handlers
MyEvent?.Invoke();
}
}
class ProgramTest
{
private Action handler;
public ProgramTest()
{
handler = Print;
}
public void AddMethod()
{
Program.MyEvent += handler; // regsiter the execute-delegate to the event
// or directly: Program.MyEvent += Print;
}
public void Print()
{
Console.WriteLine("test");
Console.ReadLine();
}
}
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