正確的方法比較通用類型

Question

在通用方法中，我必須爲每個類型執行不同的操作。我這樣做：

public static T Foo<T>(string parameter) 
    { 
      switch (typeof(T).Name) 
      { 
       case "Int32": 
        ... 
        break; 

       case "String": 
        ... 
        break; 

       case "Guid": 
        ... 
        break; 

       case "Decimal": 
        ... 
        break; 
      } 
    } 

有沒有更好的方式來知道類型T？如果（T爲int）不起作用，則爲。

Answer 1

這將是更好的組合使用if與typeof(<the type to test for>)：

if(typeof(T) == typeof(int)) 
{ 
    // Foo has been called with int as parameter: Foo<int>(...) 
} 
else if(typeof(T) == typeof(string)) 
{ 
    // Foo has been called with string as parameter: Foo<string>(...) 
} 

Answer 2

如何：

switch (Type.GetTypeCode(typeof(T))) { 
    case TypeCode.Int32: 
     break; 
    case TypeCode.String: 
     break; 
} 

這隻適用於在TypeCode枚舉中定義雖然基本類型（其中唐不包括Guid）。對於其他情況，if (typeof(T) == typeof(whatever)）是檢查類型的另一種好方法。

Answer 3

創建Dictionary<Type, Action<object>：

var typeDispatcher = new TypeDispatcher(); 

typeDispatcher.BringTheAction("Hello World"); 
typeDispatcher.BringTheAction(42); 
typeDispatcher.BringTheAction(DateTime.Now); 

：

class TypeDispatcher 
{ 
    private Dictionary<Type, Action<object>> _TypeDispatchers; 

    public TypeDispatcher() 
    { 
     _TypeDispatchers = new Dictionary<Type, Action<object>>(); 
     // Add a method as lambda. 
     _TypeDispatchers.Add(typeof(String), obj => Console.WriteLine((String)obj)); 
     // Add a method within the class. 
     _TypeDispatchers.Add(typeof(int), MyInt32Action); 
    } 

    private void MyInt32Action(object value) 
    { 
     // We can safely cast it, cause the dictionary 
     // ensures that we only get integers. 
     var integer = (int)value; 
     Console.WriteLine("Multiply by two: " + (integer * 2)); 
    } 

    public void BringTheAction(object value) 
    { 
     Action<object> action; 
     var valueType = value.GetType(); 

     // Check if we have something for this type to do. 
     if (!_TypeDispatchers.TryGetValue(valueType, out action)) 
     { 
      Console.WriteLine("Unknown type: " + valueType.FullName); 
     } 
     else 
     { 
      action(value); 
     } 
    } 

這可以隨後通過所謂的