为什么从C＃4.0使用COM库需要如此大量地使用动态类型？ [英] Why do COM libraries used from C# 4.0 require such heavy use of dynamic types?
问题描述
在C＃4.0演示中，我看到许多使用动态类型的代码。例如，以下代码设置Excel单元格的值：
In the C# 4.0 demos, I'm seeing lots of code that uses the dynamic type. For example, the following code sets the value of an Excel cell:
excel.Cells [1，1] .Value = ...
excel.Cells[1, 1].Value = ...
但是，你也可以使用一个转换以早期绑定的方式访问单元格：
However, you can also access the cell in an early bound manner with a cast:
（Range）excel.Cells [ 1]）。Value = ...;
((Range)excel.Cells[1, 1]).Value = ...;
为什么Excel COM库首先将Cell类型描述为Range类型？类似地，以下方法的所有参数都是动态的：
Why don't the Excel COM library just describe the Cell type as a Range type in the first place? Similarly, all the arguments to the following method are dynamic:
excel.ActiveWorkbook.Charts.Add（...）
excel.ActiveWorkbook.Charts.Add(...)
为什么参数不是静态的？看看Excel对象模型，到处都有动态类型。这是由于在COM的表现力的限制？在COM库中使用动态类型而不是静态类型时，是否有模式？
Why couldn't the arguments have been static? Looking at the Excel object model, there are dynamic types everywhere. Is this due to limitations in the expressiveness in COM? Is there a pattern to when dynamic types rather than static types are used in COM libraries?
推荐答案
在C＃4.0演示中，我看到许多使用动态类型的代码。
In the C# 4.0 demos, I'm seeing lots of code that uses the dynamic type.
由于 是C＃4.0中最大的变化之一，如果这不是，我会非常惊讶。 不意味着您应立即开始使用动态编写所有代码 - 只是您应该可以识别可能有用。
Since dynamic is one of the biggest changes in C# 4.0, I'd be hugely surprised if this wasn't the case. That doesn't mean you should immediately start writing all your code with dynamic - simply that you should recognise when it might be useful.
当然，方差和可选/命名参数的更改也很受欢迎，但是做一个更短的演示。
The variance and optional/named argument changes are appreciated too, of course - but make a much shorter demo.
历史上，Office（特别是）一直是这样的一个猪，对于自动化Office的人来说这是一个大事。
Historically, Office (in particular) has been such a pig to program against that this is a "big thing* for people who automate Office.
- 消费COM（特别是Office）的人
- 消费DLR类型的人（IronPython等）
- 到动态系统如javascript（Silverlight等）
我个人认为动态彻底改变了我在C＃中编程的方式，但对某些人来说是很大的：
Personally, I don't expect dynamic to revolutionise the way I program in C#, but it is big for some people:
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