在我们的一个项目中，有很多代码看起来像这样:
internal static class Extensions
{
public static string AddFoo(this string s)
{
if (s == null)
{
return "Foo";
}
return $({s}Foo);
}
}
除了“以后更容易将类型公开”之外，还有其他明确的原因吗?
我怀疑它只在非常奇怪的边缘情况下(在Silverlight反射)或根本不重要。
当前回答
I think I have an additional opinion on this. At first, I was wondering about how it makes sense to declare something to public in an internal class. Then I have ended up here, reading that it could be good if you later decide to change the class to public. True. So, a pattern formed in my mind: If it does not change the current behavior, then be permissive, and allow things that does not makes sense (and does not hurt) in the current state of code, but later it would, if you change the declaration of the class.
是这样的:
public sealed class MyCurrentlySealedClass
{
protected void MyCurretlyPrivateMethod()
{
}
}
According to the "pattern" I have mentioned above, this should be perfectly fine. It follows the same idea. It behaves as a private method, since you can not inherit the class. But if you delete the sealed constraint, it is still valid: the inherited classes can see this method, which is absolutely what I wanted to achieve. But you get a warning: CS0628, or CA1047. Both of them is about do not declare protected members in a sealed class. Moreover, I have found full agreement, about that it is senseless: 'Protected member in sealed class' warning (a singleton class)
因此，在这个警告和相关的讨论之后，我决定在一个内部类中使所有内容都变得内部或更少，因为它更符合那种思维方式，而且我们不会混合不同的“模式”。
其他回答
Internal表示只能从同一程序集中访问成员。该程序集中的其他类可以访问内部公共成员，但不能访问私有成员或受保护成员(无论是否是内部成员)。
如果类是内部的，那么从可访问性的角度来看，将方法标记为内部的还是公共的并不重要。但是，如果类是公共的，那么使用您将使用的类型仍然是好的。
虽然有些人说，这使得从内部到公开的过渡更加容易。它也作为方法描述的一部分。内部方法通常被认为是不安全的，不受约束的访问，而公共方法被认为是(大多数)自由游戏。
通过像在公共类中那样使用内部类或公共类，可以确保您传达了预期的访问风格，同时也简化了将来使类成为公共类所需的工作。
I often mark my methods in internal classes public instead of internal as a) it doesn't really matter and b) I use internal to indicate that the method is internal on purpose (there is some reason why I don't want to expose this method in a public class. Therefore, if I have an internal method I really have to understand the reason why it's internal before changing it to public whereas if I am dealing with a public method in an internal class I really have to think about why the class is internal as opposed to why each method is internal.
There does be a difference. In our project we have made a lot of classes internal, but we do unit test in another assembly and in our assembly info we used InternalsVisibleTo to allow the UnitTest assembly to call the internal classes. I've noticed if internal class has an internal constructor we are not able to create instance using Activator.CreateInstance in the unit test assembly for some reason. But if we change the constructor to public but class is still internal, it works fine. But I guess this is a very rare case (Like Eric said in the original post: Reflection).
我怀疑“以后公开类型会更容易吗?”
作用域规则意味着该方法只能作为内部方法可见——因此将方法标记为公共方法还是内部方法并不重要。
我想到的一种可能是，类是公共的，后来改为内部的，开发人员没有费心去更改所有的方法可访问性修饰符。
