确定泛型参数是否为 Nullable 类型 [英] Determine if a generic param is a Nullable type

问题描述

我有以下VB.NET函数，例如:

I have the following VB.NET function, for example:

Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TData

End Sub

如何在函数中确定 TData 是否为 NULLable 类型?

How do I, in a function, determine if TData is a NULLable Type?

推荐答案

一种方法是:

If Nullable.GetUnderlyingType(GetType(TData)) <> Nothing

...至少，C# 是:

... at least, the C# is:

if (Nullable.GetUnderlyingType(typeof(TData)) != null)

假设您在询问它是否为可空值类型.如果您问它是可空值类型还是类，那么 C# 版本将是:

That's assuming you're asking whether it's a nullable value type. If you're asking whether it's a nullable value type or a class then the C# version would be:

if (default(TData) == null)

但我不确定简单的 VB 翻译是否适用于那里，因为Nothing"在 VB 中略有不同.

but I'm not sure whether a simple VB translation would work there, as "Nothing" is slightly different in VB.

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