与私有接口比较 [英] Comparing with a private interface

问题描述

我有两个对象。 key1 的类型为 * rsa.PublicKey 。 key2 是 * ssh.PublicKey 类型，它是隐藏 * ssh.rsaPublicKey 对象。 ssh.rsaPublicKey 定义为：

I have two objects. key1 is of type *rsa.PublicKey. key2 is of type *ssh.PublicKey which is an interface hiding a *ssh.rsaPublicKey object. ssh.rsaPublicKey is defined as:

type ssh.rsaPublicKey rsa.PublicKey

它还有一些额外的方法。但是，由于该类是未导出，我不能将任一键转换为 ssh.rsaPublicKey ，我不能转换 key2 到 rsa.PublicKey ，因为它不实现 ssh.PublicKey ，我可以'从 key2 访问 N 或 e 不应该知道我有一个 rsaPublicKey 对象。

And it has a few extra methods. However, I can't cast either key to an ssh.rsaPublicKey since that class is "not exported", I can't cast key2 to an rsa.PublicKey since that doesn't implement ssh.PublicKey, and I can't access the N or e from key2 because I am not supposed to know I have an rsaPublicKey object.

我应该如何比较 key1 和 key2 是否相同？

How am I supposed to compare that key1 and key2 are the same key?

推荐答案

如前所述，您无法使用类型声明，因为您无法参考到未导出的类型 ssh.rsaPublicKey 。

As you mentioned, you can't use type assertion because you can't refer to the unexported type ssh.rsaPublicKey.

您可以使用 反映 包。

What you want is possible with using the reflect package.

由于 rsa.PublicKey 是 ssh.rsaPublicKey 的底层类型，指向包装在 key2 中的值可以转换为 rsa.PublicKey 。获取 reflect.Value 后您的 key2 ，使用指向 .Elemrel =nofollow> Value.Elem（） 。此值可转换为 rsa.PublicKey 类型的值。您可以使用 Value.Convert（） 到动态，在运行时将其转换为 rsa.PublicKey 。获得后，您可以使用 reflect.DeepEquals（） 进行比较，或手动比较。

Since rsa.PublicKey is the underlying type of ssh.rsaPublicKey, the pointed value wrapped in key2 can be converted to rsa.PublicKey. Once you obtain reflect.Value of your key2, "navigate" to the pointed value using Value.Elem(). This value is convertible to a value of type rsa.PublicKey. You may use the Value.Convert() to "dynamically", at runtime convert it to rsa.PublicKey. Once you have it, you can use reflect.DeepEquals() to do the comparison, or compare it manually.

这是它的样子：

key1 := &rsa.PublicKey{N: big.NewInt(123), E: 10}
key2, _ := ssh.NewPublicKey(&rsa.PublicKey{N: big.NewInt(123), E: 10})


key2conv := reflect.ValueOf(key2).Elem().
    Convert(reflect.TypeOf(rsa.PublicKey{})).Interface()
// key2conf is an interface{}, wrapping an rsa.PublicKey

// Comparision with DeepEqual
fmt.Println(reflect.DeepEqual(*key1, key2conv))

// Comparing manually:
key22 := key2conv.(rsa.PublicKey)
fmt.Println(key1.N.Cmp(key22.N)) // Int.Cmp() returns 0 if equal
fmt.Println(key1.E == key22.E)

请注意，当手动比较时，比较 PublicKey.N 是 * big.Int 类型 - 您需要使用 Int.Cmp（） 方法，因为比较指针会比较内存地址，而不是指向的值。 如果两个值相等，则Int.Cmp（）返回 0 。

Note that when comparing manually, comparing the PublicKey.N field –which is of type *big.Int– you need to use the Int.Cmp() method because comparing pointers compares the memory addresses, not the pointed values. And Int.Cmp() returns 0 if the 2 values are equal.

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