c# - 我应该使用动态关键字来优化转化吗？

Question

我有简单的类层次结构(基类 A、派生类 B:A、派生类 C:A 等)。我有以下代码:

void computation(A base_class)
{
    if (base_class is B)
    {
        //Do some stuff with (base_class as B)
    }
    if (base_class is C)
    {
        //Do some stuff with (base_class as C)
    }
}

我想起了c#语言的dynamic关键字。据我了解，我可以使用以下代码(以优化额外转化)。

void computation(A base_class)
{
    dynamic temp = base_class as B;
    if (temp != null)
    {
        //Do some stuff with temp
    }
    temp = base_class as C;
    if (temp != null)
    {
        //Do some stuff with (base_class as C)
    }
}

哪种变体更适合使用？这些方法的性能如何？

Answer 1

这听起来像是过早的优化，我不喜欢这里的 dynamic 用法。

还要记住 dynamic 会做一些特定的事情，比如(引用自 MSDN):

The dynamic type enables the operations in which it occurs to bypass compile-time type checking. Instead, these operations are resolved at run time.

所以我想绕过编译时类型检查不是你想要的。

我建议改用 var。恕我直言，它提高了可读性，调试更容易，使用 as 而不是 is + casting 也更快一些。

void computation(A base_class)
{
    var b = base_class as B;
    if (b != null)
    {
        //Do some stuff with temp
    }
    var c = base_class as C;
    if (c != null)
    {
        //Do some stuff with (base_class as C)
    }
}