如何创建可以使用两个名称空间之一的类？

Question

I have a project which contains a class that draws on a graph. The class looks like this:-

using System.Web.UI.DataVisualization.Charting;

namespace MyNameSpace
{
    public static class Utilities
    {
        public static void DrawOnGraph (Chart ourChart,
                                        // ...more parameters...
                                        )
        {
            ChartArea our_area = new ChartArea("Main");
            // Draw things
        }
    }
}

This is driven by a web application contained in another project in the same solution. I now have a requirement to create a forms application which will draw precisely the same graph using precisely the same inputs on to a web form. I wish include the project into a second solution. But the class needs to look like this:-

using System.Windows.Forms.DataVisualization.Charting;

namespace MyNameSpace
{
    public static class Utilities
    {
        public static void DrawOnGraph (Chart ourChart,
                                        // ...more parameters...
                                        )
        {
            ChartArea our_area = new ChartArea("Main");
            // Draw things
        }
    }
}

I would like to know if it would be possible to use the same project/class/code for both, as naturally I don't want to cut'n'paste the code into two different places, and the only difference is the using directive.

I don't see how I can use generics as there are declarations inside the function of objects in the (alternative) namespaces, such as the ChartArea shown above. I can't see a way to use conditional compilation as which line is required depends on which solution the project is in, not the project itself, and it can't refer to the caller project as that would create a circular reference. Neither can I cast a web graph to a windows graph.

The best I have been able to manage is to supply both using directives but comment one of them out according to which solution I am currently working on. But that doesn't seem very satisfactory to me. Is there a better way? Or should I not be so idle and write the code twice?

Answer 1

You can create your own abstraction on top of drawing logic and use wrapper pattern to encapsulate both charts. Then you would code against your abstraction and provide implementation form each forms and web project. I assume the drawing graph logic in complicated enough to justify this approach. If you implement this it will allow you to introduce changes in graph in one place and it will affect both applications.

Answer 2

The best soultion I can think of is to create wrapper-interfaces for classes, that both System.Web.UI.DataVisualization.Charting and System.Windows.Forms.DataVisualization.Charting provide/require. Then provide two implementations of the interface: one for Forms and one for UI. Having that, your Utilities can call interface methods without knowing the exact implementation, and share code for both UI and Forms.

Answer 3

One is for Web

using System.Web.UI.DataVisualization.Charting;

and the other one for windows

using System.Windows.Forms.DataVisualization.Charting;

the issue is that they will be using classes that are relevant for their platform so I don think you able to achieve it

My advice would be to separate out the common functionality in to a library which is not dependant for Web or Windows and use this in to two different solution one for web and the other for windows, this way alteast you have reduced the code repetition twice

Update :

Another option is to write it as Windows Control library and then make it available in the web application as a DLL. Please look at this example http://www.beansoftware.com/ASP.NET-Tutorials/Place-Windows-Control-To-Web-Form.aspx

Answer 4

You can use conditional compilation if your code calls the 'identical' parts of the respective APIs of Web.UI and Windows.Forms Charting, that include operations with Series, ChartArea, etc.

Simply compile the code twice: once using Web.UI Charting and the other using Windows.Forms Charting. Use conditional compilation to enable/disable assembly references so one assembly targets applications based on WinForms and the other WebUI Charting apps.

Alternatively, in some quick-and-dirty situations you could get by with just the Windows.Forms Charting API, and whenever html is needed, eg a src attribute for an img element, merely use Chart.SaveImage (..), and so on. But this has drawbacks.

Both of these alternatives are limiting because the respective APIs and functionalities of Web.UI and Windows.Forms Charting don't overlap enough. And SaveImage() is additionally limiting because you don't want your web app burdened by the Windows.Forms assemblies and extraneous operations.

Nonetheless the conditional compilation approach will work even if the web and forms assemblies diverge. You will be able to maintain shared codes (but conditionally compiled for web or forms), but each library will accumulate new code specific to its web or forms target. This approach works best with a good approach to build configuration. If you have a good approach to build configuration I think it will be easier to maintain and extend than other approaches.