泛型类的静态成员是否绑定到特定实例? [英] Are static members of a generic class tied to the specific instance?

问题描述

这与其说是一个真正的问题，不如说是一个文档.这似乎还没有在 SO 上得到解决(除非我错过了)，所以这里是:

This is more of a documentation than a real question. This does not seem to have been addressed on SO yet (unless I missed it), so here goes:

想象一个包含静态成员的泛型类:

Imagine a generic class that contains a static member:

class Foo<T> {
    public static int member;
}

对于每个特定的类，是否有一个新的成员实例，或者所有 Foo 类型的类是否只有一个实例?

Is there a new instance of the member for each specific class, or is there only a single instance for all Foo-type classes?

它可以很容易地通过这样的代码验证:

It can easily be verified by code like this:

Foo<int>.member = 1;
Foo<string>.member = 2;
Console.WriteLine (Foo<int>.member);

结果是什么，这种行为记录在哪里?

What is the result, and where is this behavior documented?

推荐答案

static 字段在所有相同类型的实例之间共享.Foo 和 Foo 是两种不同的类型.这可以通过以下代码行来证明:

A static field is shared across all instances of the same type. Foo<int> and Foo<string> are two different types. This can be proven by the following line of code:

// this prints "False"
Console.WriteLine(typeof(Foo<int>) == typeof(Foo<string>));

至于记录的位置，可在 C# 语言规范(针对 C# 3)的 1.6.5 字段 部分中找到以下内容:

As for where this is documented, the following is found in section 1.6.5 Fields of the C# Language Specification (for C# 3):

静态字段仅标识一个存储位置.不管有多少创建类的实例，只有一个副本静态字段.

A static field identifies exactly one storage location. No matter how many instances of a class are created, there is only ever one copy of a static field.

如前所述；Foo 和 Foo 不是同一个类；它们是由同一个泛型类构造的两个不同的类.上述文档的第 4.4 节概述了这是如何发生的:

As stated before; Foo<int> and Foo<string> are not the same class; they are two different classes constructed from the same generic class. How this happens is outlined in section 4.4 of the above mentioned document:

泛型类型声明本身，表示一个未绑定的泛型类型被用作蓝图"以形成许多不同类型，通过申请类型参数.

A generic type declaration, by itself, denotes an unbound generic type that is used as a "blueprint" to form many different types, by way of applying type arguments.

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