带 Or 的通用类型约束

发布于 2024-11-25 01:47:20 字数 265 浏览 1 评论 0原文

public T CreateForm<T>() where T: BaseForm, BaseMainForm

我知道上面的意思是T是一个BaseForm和一个BaseMainForm。但是是否也可以限制 T 必须是 BaseForm 或一个 BaseMainForm ？

原文

public T CreateForm<T>() where T: BaseForm, BaseMainForm

I know the above means where T is a BaseForm and a BaseMainForm. But is it also possible to make the constraint that T has to be either a BaseForm or a BaseMainForm?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

紧拥背影 2024-12-02 01:47:20

不，这在 C# 中是不允许的。编译器使用泛型约束来确定泛型方法内的 T 上可用的操作 - 因此允许或表达式将不是类型安全的。

如果您需要此功能，请考虑添加一个涵盖 BaseForm 和 BaseMainForm 公共部分的接口，并将其应用为通用约束。这样，接口定义了方法 CreateForm 所需的约定 - 并且您必须简单地确保您传入的 Form 实现该接口。

像这样的东西：

public interface IBaseForm 
{
    Foo();
}

class BaseForm : IBaseForm {}
class BaseMainForm : IBaseForm {}

public T CreateForm<T>() where T : IBaseForm

No, that is not allowed in C#. The compiler uses the generic constraint to determine what operations is available on T within the generic method - so allowing an or expression would not be type safe.

If you need this, consider adding an interface covering the common parts of BaseForm and BaseMainForm, and apply that as the generic constraint. This way, the interface defines the contract of what the method CreateForm<T> needs - and you must simply make sure that the Form's you pass in implement the interface.

Something like:

public interface IBaseForm 
{
    Foo();
}

class BaseForm : IBaseForm {}
class BaseMainForm : IBaseForm {}

public T CreateForm<T>() where T : IBaseForm

回复收藏 0 原文