使用泛型与As运算符 [英] Using Generic Types with As operator

问题描述

尝试使用as与generic时出现编译器错误。既然我不能按照我想要的方式来做，那么更好的方法是什么......？我想检查5-6种类型，确定我可以使用一种方法，看看它是否为空。

I get a compiler error when Trying to use a generic with as. Since i can't do it the way I want to, what is a better way..? I wanted to check through 5-6 types, figuring i can use one method and see if it is null or not.

    T CheckIsType<T>(Thing thing)
    {
        return thing as T;
    }

确切的错误文字：

exact error text:

Error   1   The type parameter 'T' cannot be used with     the 'as' operator because it does not have a class type     constraint nor a 'class' constraint.

推荐答案

只需添加抱怨不存在的约束：

Just add the constraint it's complaining about not being there:

T CheckIsType<T>(Thing thing)
    where T: class
{
    return thing as T;
}

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