不可修改的变量 [英] variable that can't be modified

问题描述

C＃是否允许使用无法修改的变量？就像 const ，但是不必在声明时给它赋值，该变量没有任何默认值，而只能在运行时赋值一次（编辑：可能不是从构造函数）。还是不可能？

Does C# allow a variable that can't be modified? It's like a const, but instead of having to assign it a value at declaration, the variable does not have any default value, but can only be assigned a value once at runtime ( and possibly not from constructor). or is this not possible?

推荐答案

您可以创建自己的提供此类功能的泛型类，但这可能会显得过大。 / p>

You could create your own generic class that provided this functionality, but that might be overkill.

public class SetValueOnce<T>
{
    public bool _set;
    private T _value;

    public SetValueOnce()
    { 
      _value = default(T);
      _set = false;
    }

    public SetValueOnce(T value)
    { 
      _value = value;
      _set = true;
    }

    public T Value
    {
      get
      {
          if(!_set)
             throw new Exception("Value has not been set yet!");
          return _value;
      {
      set
      {
         if(_set)
             throw new Exception("Value already set!");
         _value = value;
         _set = true;
      }
   }
}

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