Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim c As New Scripting.Dictionary
' Dim c As New Dictionary(Of String, Long)
Dim w As Long
Dim t As Double
Dim p As Long
t = Microsoft.VisualBasic.Timer
For w = 1 To 10000000
p = c("QQ")
MsgBox(CLng((Microsoft.VisualBasic.Timer - t) * 10000) / 10000, , "AAAA")
COM Interoperability is the feature of Microsoft .NET that allows managed .NET code to interact with unmanaged code using Microsoft's Component Object Model semantics.
This article is geared towards C# programmers who are familiar with developing COM components and familiar with the concept of an interface. I'll review some background on COM, explain how C# interacts with COM, and then show how to design .NET components to smoothly interact with COM.
For those die-hard COM experts, there will be some things in this article that are oversimplified, but the concepts, as presented, are the important points to know for those developers supplementing their COM code with .NET components.
.NET Interfaces and Classes
The basis for accessing .NET objects either from other .NET code or from unmanaged code is the Class. A .NET class represents the encapsulation of the functionality (methods and properties) that the programmer wants to expose to other code. A .NET interface is the abstract declaration of the methods and properties that classes which implement the interface are expected to provide in their implementations. Declaring a .NET interface doesn't generate any code, and a .NET interface is not callable directly. But any class which implements ("inherits") the interface must provide the code that implements each of the methods and properties declared in the interface definition.
Microsoft realized that the very first version of .NET needed a way to work with the existing Windows technology used to develop applications over the past 8+ years: COM. With that in mind, Microsoft added support in the .NET runtime for interoperating with COM - simply called "COM Interop". The support goes both ways: .NET code can call COM components, and COM code can call .NET components.
Using the code
Steps to create a Managed .NET C# COM Object:
Open VS.NET2003->New Project->Visual C# Projects->Class Library.
Project name: MyInterop.
Create MyDoNetClass.cs file, and add the following lines of code:
Create an Interface IMyDotNetInterface.
Create a class MyDoNetClass.
Add the following line for MyDotNetClass:
Although a .NET class is not directly invokable from unmanaged code, Microsoft has provided the capability of wrapping a .NET interface in an unmanaged layer of code that exposes the methods and properties of the .NET class as if the class were a COM object. There are two requirements for making a .NET class visible to unmanaged code as a COM object:
You have to add GUIDs - Globally Unique Identifiers - into your code for the interface and the class separately, through a GUID tool.