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Creating a class library

From: Visual Studio 2010 Essential Training

Video: Creating a class library

It is common nowadays to create a separate DLL that contains shared logic for applications. That way you have a centralized assembly that contains the compiled code. You also have one project where you can write and debug that shared code. In .NET, you create a class library to accomplish this. When you compile that class library, it generates a DLL. I'm inside Visual Studio, and I've opened this Solution called CreateClassLibrary. There are two projects already in here. There is a Visual Basic console application, and there is a WPF application that's written in C#.

Creating a class library

It is common nowadays to create a separate DLL that contains shared logic for applications. That way you have a centralized assembly that contains the compiled code. You also have one project where you can write and debug that shared code. In .NET, you create a class library to accomplish this. When you compile that class library, it generates a DLL. I'm inside Visual Studio, and I've opened this Solution called CreateClassLibrary. There are two projects already in here. There is a Visual Basic console application, and there is a WPF application that's written in C#.

Now I'm going to add a shared library. I'm going to go to the solution, right- click and choose to add a new project. I'm then going to choose this Class Library Template and then type in the name TextLibrary for the Name, and then click OK. Now, I'm going to compile the application to show you what happens. When I build the solution, it's going to compile all three projects. And if I right-click on the TextLibrary and choose Open Folder in Windows Explorer, you'll see that if I drill down into the bin folder and then the Debug folder, that it's creating this DLL.

Now, I'm going to come back to this folder in a minute. Let me switch to Visual Studio. I'm going to generate a class called LoremGenerator, which generates random sentences of Latin words. So, I think I should rename this Class file. So I'll come over here to my project and type in "LoremGenerator", and then press Enter. Visual Studio then prompts me and asks me if I would also like to rename the class inside that file.

That seems like a great idea to me. So I'm going to click Yes. Now you see that it has this new LoremGenerator class. I'm not going to write all the code today live. I do have the code up here in this Assets folder. There is a TXT file in here, which I'm going to double-click on. Then I'm going to copy all of the code in this class. Back to my LoremGenerator.cs file. Then I'll replace these three lines of code, Ctrl+V. I won't go through all of the code, but let me just point out that there are two methods I'm going to use: the GetWords method where I pass the numberOfWords in, and it gives me back say eight words, and a GetSentence, which has the same parameter, but this time of course it's going to put a period on the end of that sentence.

Now I'm ready to use this. This is a C# library. I'm going to go to my Visual Basic Application and add a reference to this library. I'm going to right-click, and I'm going to choose to add a reference, and I'm going to click the Browse button, and then I'm going to go back to Windows Explorer and copy this path to that Debug folder. Copy it, Ctrl+C. Switch back here, and I'm going to paste it down here where it says File name, and then press Enter. And there is the DLL that I want to have the reference to.

So I'll choose that one and then click OK. Now, just for good measure, I'm going to recompile my application and click Yes here. So now when I compile this application, it's telling it to make sure that I can use the code that's inside that DLL. Let's use it. I'm going to double-click on Module1.vb, and then I'm going to go here, and I'm going to declare an instance of that generator, Dim g As New TextLibrary. There is my namespace. There is my class.

Now I'm going to write to the console, and I'll also read from the console. Next, I'm going to go onto line 6, and I'm typing in "g.GetSentence", and let's say I wanted eight words out of that.

Let's test this out. Debug > Start Debugging, and there is my randomly generated sentence, including the period on the end. Next, I'm going to switch over to the C# application-- that would be this one down here WpfClient--and I'm going to open the MainWindow.xaml.cs file. Then inside my constructor, I will declare the C# version of that variable, var g = new.

Well, this isn't going to work, because I forgot one step. I forgot to add the reference to the library. See, I'm getting a red squiggle here. So let me comment this code out and then go over to my References folder and show you an alternative way of writing a reference. Right-click > Add Reference. Last time I browsed out and pointed to a physical location, but Visual Studio can simplify my life by letting me do something called a project reference. I click here and then I say whenever you compile this TextLibrary, I would like to know about it and get a fresh copy of that DLL.

So, I click OK here, and then if you scroll down and look at the Reference here, you'll notice it says Copy Local equal True. So not only will it update the DLL, but it'll copy the DLL into the same folder as my application. So, when I deploy the app, I've got both files. Now that I've added that Reference, I can go back to this code that wasn't working before, uncomment it, and then go to this line. There is the TextLibrary I was looking for, and then period, and there is the LoremGenerator, and then finally, "var words = g.GetWords".

And there is my new function. So, the takeaway from this is both the Visual Basic application and the C# application are sharing the code that's inside that TextLibrary DLL. As you can see, it is very easy to add references to other libraries in Visual Studio and that the Class Library template provides a trouble-free way to make that custom library.

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This video is part of

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Visual Studio 2010 Essential Training

86 video lessons · 30224 viewers

Walt Ritscher
Author

 
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  1. 2m 3s
    1. Welcome
      1m 2s
    2. Using the exercise files
      1m 1s
  2. 7m 19s
    1. Understanding the Visual Studio versions
      3m 51s
    2. Setting up your developer computer
      3m 28s
  3. 58m 2s
    1. Creating a Visual Studio project
      4m 58s
    2. Working with Solution Explorer
      6m 32s
    3. Working with big projects
      3m 53s
    4. Taking a tour of the Integrated Developer Environment (IDE)
      8m 36s
    5. Introducing drag-and-drop UI design
      7m 38s
    6. Working with the Properties window
      6m 44s
    7. Looking at Server Explorer
      7m 4s
    8. Exploring the new Help engine
      6m 41s
    9. Setting options for the IDE
      5m 56s
  4. 39m 25s
    1. Creating a simple WPF application
      1m 32s
    2. Building the UI with the editors
      9m 14s
    3. Working with the application code
      3m 37s
    4. Communicating with the web site
      7m 15s
    5. Connecting your data
      8m 4s
    6. Binding to an RSS feed
      5m 4s
    7. Packaging and deploying the application
      4m 39s
  5. 39m 46s
    1. What languages are supported in Visual Studio 2010?
      1m 17s
    2. Exploring basic settings for the Code Editor
      5m 35s
    3. Writing a C# program
      6m 48s
    4. Writing a VB program
      6m 29s
    5. Working with C++
      6m 38s
    6. Working with F Sharp
      6m 9s
    7. Font and color options
      6m 50s
  6. 1h 5m
    1. Formatting your code
      6m 43s
    2. Navigating your code
      7m 44s
    3. Using the Task List
      2m 26s
    4. Commenting your code
      2m 45s
    5. Documenting your code
      8m 26s
    6. Using IntelliSense effectively
      7m 0s
    7. Working with code snippets
      6m 25s
    8. Refactoring your code
      5m 15s
    9. Understanding code generation
      2m 10s
    10. Generating code with T4
      6m 29s
    11. Using the Class View, Class Designer, and Class Diagram tools
      5m 51s
    12. Refactoring VB with CodeRush Xpress
      4m 33s
  7. 1h 11m
    1. Working with project and item templates
      8m 38s
    2. Creating a console application
      7m 5s
    3. Creating a class library
      6m 26s
    4. Creating a web site with ASP.NET
      7m 37s
    5. Creating a rich internet application with Silverlight
      6m 57s
    6. Creating a classic Windows application with Windows Forms
      10m 31s
    7. Creating a dramatic Windows application with Windows Presentation Foundation (WPF)
      4m 41s
    8. Creating a WCF service
      9m 1s
    9. Using an existing WCF service
      6m 38s
    10. Navigation UI designs with the Document Outline view
      3m 41s
  8. 33m 18s
    1. Creating a data project with SQL Project
      6m 24s
    2. Clarifying the confusion on .NET Data
      3m 31s
    3. Using ADO.NET in your application
      6m 50s
    4. Creating typed datasets
      7m 55s
    5. Using the data binding tools
      8m 38s
  9. 30m 13s
    1. Debugging code
      9m 32s
    2. Working with the Watch and other debug windows
      7m 46s
    3. Other debugging techniques
      6m 50s
    4. IntelliTrace historical debugging in Visual Studio Ultimate
      6m 5s
  10. 17m 56s
    1. Understanding Visual Studio editions and test tools
      2m 22s
    2. Verifying your code with unit tests
      8m 58s
    3. Running performance and load tests
      6m 36s
  11. 34m 5s
    1. Building your application
      4m 19s
    2. Customizing the build process with MSBuild
      6m 36s
    3. Setting assembly information
      2m 12s
    4. Deploying a basic Windows application
      2m 19s
    5. Creating an installer with Visual Studio
      7m 39s
    6. Creating a ClickOnce application
      5m 13s
    7. Setting up IIS for deploy
      2m 9s
    8. Deploying a Silverlight or ASP.NET application
      3m 38s
  12. 14m 0s
    1. Understanding source control
      2m 9s
    2. Setting up Team Foundation Server source control
      3m 5s
    3. Using Team Foundation Server source control
      8m 46s
  13. 17m 31s
    1. Understanding the .NET Office integration
      4m 16s
    2. Making a Word 2010 application
      7m 54s
    3. Making an Excel 2010 add-in
      5m 21s
  14. 31m 34s
    1. Understanding the extensibility model in Visual Studio
      2m 17s
    2. Adding external tools to the Tools menu
      4m 42s
    3. Creating macros
      7m 16s
    4. Using the Extension Manager
      5m 1s
    5. Creating an MEF add-in
      7m 9s
    6. Deploying and installing an add-in with VSIX
      5m 9s
  15. 25m 34s
    1. Working with configuration files
      5m 37s
    2. Using the Settings Editor
      7m 30s
    3. Using the Resources Editor
      6m 59s
    4. Localizing your resources
      5m 28s
  16. 1m 17s
    1. Goodbye
      1m 17s

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