如何定义公共静态只读字段? [英] How to define a public static readonly field?

问题描述

在C#中，可以这样定义一个公共的静态只读字段:

In C#, one can define a public static readonly field like this:

namespace MyNamespace
{
    public static class MyClass
    {
        public static readonly string MyValue = "Test";
    }
}

在F#中，我能想到的与上面定义最匹配的代码是:

In F#, the code I can think of which matches the definition above best is:

namespace MyNamespace

module MyClass =
    [<Literal>]
    let MyValue = "Test"

但这实际上转换为以下C#代码段:

But this actually translates to the following C# snippet:

namespace MyNamespace
{
    public static class MyClass
    {
        public const string MyValue = "Test";
    }
}

如何在F#中定义公共静态只读字段? const 不是我的选择，因为我想

How can I define a public static readonly field in F#? const is not an option for me since I want to work with different assemblies.

推荐答案

只需删除 Literal 属性并使用一个让界值:

Just drop the Literal attribute and use a let-bound value:

module MyClass =
    let MyValue = "Test"

这将被编译为等效于仅静态获取方法的属性(ILSpy生成的C#):

This will compile as an equivalent of a static getter-only property (ILSpy-generated C#):

public static string MyValue
{
    [DebuggerNonUserCode, CompilerGenerated]
    get
    {
        return "Test";
    }
}

如果该值涉及计算(而不是像您这样的文字)，它将实际上绑定为模块(并在getter主体中引用)的内部类中的静态只读字段.您可以根据需要使用ILSpy验证自己.

If the value involves a computation (rather than being a literal as in your case), it will actually be bound as a static readonly field in the internal class underlying the module (and referred to in the getter body). You can verify that yourself with ILSpy if you like.

那是如果您对编译器生成的实际IL感兴趣的话-F#作为一种语言没有单独的只读字段概念(因为让绑定值，记录字段等是只读的)默认).它甚至没有保留关键字.

That's if you're interested in actual IL generated by the compiler - F# as a language doesn't have a separate notion of a read-only field (as let-bound values, record fields etc. are read-only by default). It doesn't even reserve the keyword.

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