如何在 C# 中将类实例声明为常量? [英] How to declare a class instance as a constant in C#?

问题描述

我需要实现这个:

static class MyStaticClass
{
    public const TimeSpan theTime = new TimeSpan(13, 0, 0);
    public static bool IsTooLate(DateTime dt)
    {
        return dt.TimeOfDay >= theTime;
    }
}

theTime 是一个常数(说真的:-)，就像 π 一样，例如，在我的情况下，从设置中读取它是没有意义的.而且我希望它被初始化一次并且永远不会改变.

theTime is a constant (seriously :-), like π is, in my case it'd be pointless to read it from settings, for example. And I'd like it to be initialized once and never changed.

但 C# 似乎不允许由函数(即构造函数)初始化常量.如何克服?

But C# doesn't seem to allow a constant to be initialized by a function (which a constructor is). How to overcome this?

推荐答案

使用 readonly 代替 const 可以初始化，之后不再修改.这就是你要找的吗?

Using readonly instead of const can be initialized and not modified after that. Is that what you're looking for?

代码示例:

static class MyStaticClass
{
    static readonly TimeSpan theTime;

    static MyStaticClass()
    {
        theTime = new TimeSpan(13, 0, 0);
    }
}

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