System.Type.Missing

最新推荐文章于 2025-03-20 07:00:00 发布

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最新推荐文章于 2025-03-20 07:00:00 发布

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文章标签： c#

原文链接：http://blog.51cto.com/zhaojie/707070

本文介绍了 System.Type.Missing 这一特殊值在含有可选参数的方法调用中的使用方法，尤其强调了它在进行 COM 互操作时的作用。此值为 C# 开发者提供了一种更为便捷的方式，尤其是在处理具有可选参数的 COM 接口时。

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System.Type.Missing

Here's one that I had never heard of until today when Dustin Campell on the Extensibillity Newsgroup pointed this out to me:

There's a special value System.Type.Missing that can be used when making method calls that contain optional parameters. This of course is tremendously useful for making COM interop calls to COM interfaces that have optional parameters.

This is something I've been struggling with quite a bit lately in my Add-In travails. Much of the documentation for Add-Ins is provided with VB or VB.NET code and much of that code uses either Option Strict Off or VBA both of which allow simply omitting of parameters. C# with managed interfaces allows no such thing, so this value just made my life a lot easier.

Amazing how easy it is to miss something so useful for so long, n'est pas?

(原文来源： http://www.west-wind.com/weblog/posts/2004/Aug/14/SystemTypeMissing)

转载于:https://blog.51cto.com/zhaojie/707070