[.NET]CallerMemberNameAttribute-可讓您取得方法呼叫端的方法或屬性名稱

2013-09-13

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.NET
2014-10-07

程式中有需要將那些屬性名稱當作參數傳給某個Method嗎? 可利用CallerMemberNameAttribute來避免寫死屬性名稱哦!

環境:.NET 4.5

MSDN上的說明 CallerMemberNameAttribute 類別 : 可讓您取得方法呼叫端的方法或屬性名稱

那要如何取得「呼叫端資訊」呢?

只要在Method中設定CallerMemberNameAttribute(要using System.Runtime.CompilerServices;)，就可以在Method中取得呼叫端資訊，如下為MSDN的範例，


//using System.Runtime.CompilerServices;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            TraceMessage("Hi, Rainmaker!");
        }

        public static void TraceMessage(string message,
        [CallerMemberName] string memberName = "",
        [CallerFilePath] string sourceFilePath = "",
        [CallerLineNumber] int sourceLineNumber = 0)
        {
            Console.WriteLine("message: " + message);
            Console.WriteLine("member name: " + memberName);
            Console.WriteLine("source file path: " + sourceFilePath);
            Console.WriteLine("source line number: " + sourceLineNumber);
        }
    }
}

那CallerMemberNameAttribute 類別適合用在那裡呢?

如果程式中有需要將那些屬性名稱當作參數傳給某個Method的話，就得適合用這個，您就不需要在程式中寫死屬性名稱，如實作 INotifyPropertyChanged 的Class，原本在屬性改變時，要呼叫OnPropertyChanged("屬性名稱");。

有了CallerMemberNameAttribute 類別就可以不用在程式中寫死屬性名稱了，OnPropertyChanged();，如下，


public string SomeProperty
{
    get
    {
        return _someProperty;
    }
    set
    {
        if (value != _someProperty)
        {
            _someProperty = value;
            //You dont need to pass string of the propertyname, compiler will do for us.
          //OnPropertyChanged("SomeProperty"); - no need any more
            OnPropertyChanged();
        }
    }
}

/// <summary>

/// Notifies when the property is changed

/// </summary>

/// <param name="propertyName">New Features in C# 5, that you can easely skip writing string of property name.</param>

protected void OnPropertyChanged([CallerMemberName] string propertyName = null)

{

//whatever you need to be called

}

詳細請參考「New feature in C# 5.0 – [CallerMemberName]」。