WPF - Class inheriting from a variable class

Question

I have an application that can display items in two different ways, in rows using a StackPanel or icons using a WrapPanel. Which way it displays these items depends on a config setting. To populate these panels I have two seperate classes one inherits from the WrapPanel the other from the StackPanel. I was able to cut down on duplicated code using an Inferface. However I still had a lot of duplicated code the only difference between the code is the references to StackPanel or WrapPanel.

What I would really like to do is create a class that inherits from either the StackPanel or WrapPanel depending on the config setting.

public class ContainerBase : <wrap or stack>
{

//Do stuff!

}

Is this possible? Am I approaching this incorrectly?

This looks like workaround to me ... don't think that this is correct approach. How about using composition but not inheritance here? — alex.b
– alex.b, Commented Sep 6, 2012 at 14:58
@KarelFrajtak, templates and styles(+template selector) was first things that I thought about, but I don't have enough experience with them to be able to recommend smth useful in this case. But essentially yes - templates and styles sounds reasonable. — alex.b
– alex.b, Commented Sep 6, 2012 at 15:19
@Fred, I've added answer+code to illustrate what I meant in first comment — alex.b
– alex.b, Commented Sep 6, 2012 at 15:20
You definitely should learn how to use DataTemplateSelector and MVVM to work with WPF, it require much less code than what you are trying to do. — JoanComasFdz
– JoanComasFdz, Commented Sep 6, 2012 at 15:24

alex.b · Accepted Answer · 2012-09-06 15:20:26Z

When I said "composition but not inheritance" in first comment, I meant smth like the following:

public class PanelPresentatinLogic
{
    public Panel Panel{get;set;}     

    public void DoSomeDuplicatingStuff()
    {
        //Do stuff! with Panel
    }    
}

public class SortOfStackPanel : StackPanel
{
    private readonly PanelPresentatinLogic _panelPresentatinLogic;

    public SortOfStackPanel(PanelPresentatinLogic presentationLogic)
    {
        _panelPresentatinLogic = presentationLogic;
        _panelPresentatinLogic.Panel = this;
    }

    public void DoSomeDuplicatingStuff()
    {
        _panelPresentatinLogic.DoSomeDuplicatingStuff();
    }
}


public class SortOfWrapPanel : WrapPanel
{
    private readonly PanelPresentatinLogic _panelPresentatinLogic;

    public SortOfWrapPanel(PanelPresentatinLogic presentationLogic)
    {
        _panelPresentatinLogic = presentationLogic;
        _panelPresentatinLogic.Panel = this;
    }

    public void DoSomeDuplicatingStuff()
    {
        _panelPresentatinLogic.DoSomeDuplicatingStuff();
    }
}

public class UsageSample
{
    public void PopulateCollectionOfItemsDependingOnConfigHopeYouveGotTheIdea()
    {
        string configValue = configuration["PanelKind"];
        PanelPresentatinLogic panelPresentatinLogic = new PanelPresentatinLogic();

        Panel panel = configValue == "Wrap" 
            ? new SortOfWrapPanel(panelPresentatinLogic)
            : new SortOfStackPanel(panelPresentatinLogic);
        // TODO: add panel to GUI
    }
}

Raj Ranjhan · Accepted Answer · 2012-09-06 15:00:49Z

1

You can use Generics for this;

public class ContainerBase<T>  where T : Panel

You can then use the config setting to initialize the right type.

edited Sep 6, 2012 at 15:00

answered Sep 6, 2012 at 14:55

Raj Ranjhan

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1 Comment

Servy Over a year ago

This assumes (possibly correctly) that the OP only needs methods from either class that are provided by Panel, or can refactor his code to make that happen.

JoanComasFdz · Accepted Answer · 2012-09-06 15:21:03Z

1

In WPF you are intended to not use controls to populate itself. Instead, use MVVM pattern.

You can achieve your goal with only one class providing the data (tipically an ObservableCollection) and loading that "view mode variable" into a property at MVVM.

Then you can use a an ItemsPanel with an DataTemplateSelector to select the view.

answered Sep 6, 2012 at 15:21

JoanComasFdz

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Comments

syned · Accepted Answer · 2012-09-06 15:09:41Z

0

May be you can use Panel?

    public class ContainerBase : <wrap or stack>
    {

    //Do stuff!

    }

answered Sep 6, 2012 at 15:09

syned

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