return values from a class

Question

How can i return a value from a a function in a Sealed Partial class?

I use the usercontrols like this. I have a usercontrol that calls another one that is a list. When i selected a row from this list, i call SelectionChanged="RadGrid1_SelectedIndexChanged" and it saves on a variable of type Templates the row i want to save. (Until here there is no problem)

When in the mainpage i try to access to that variable, it always returns me null. (Problem here)

UserControls:

<UserControl
x:Class="Stuff.Grouping.TableControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Stuff.Grouping"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300"
d:DesignWidth="400">

<Grid>
    <SemanticZoom ScrollViewer.HorizontalScrollMode="Disabled" ScrollViewer.VerticalScrollMode="Disabled">
        <SemanticZoom.ZoomedInView>
            <local:GroupingZoomedInView Margin="0 0 30 50"/>
        </SemanticZoom.ZoomedInView>
        <SemanticZoom.ZoomedOutView>
            <GridView Margin="30 30 30 50">
                <GridView.ItemsPanel>
                    <ItemsPanelTemplate>
                        <WrapGrid Orientation="Horizontal" MaximumRowsOrColumns="7"/>
                    </ItemsPanelTemplate>
                </GridView.ItemsPanel>
                <GridView.ItemTemplate>
                    <DataTemplate>
                        <Border Background="#FF3399FF" MinWidth="100" MinHeight="100">
                            <TextBlock Text="{Binding}" FontSize="60" Margin="10"/>
                        </Border>
                    </DataTemplate>
                </GridView.ItemTemplate>
            </GridView>
        </SemanticZoom.ZoomedOutView>
    </SemanticZoom>
</Grid>
</UserControl>

GroupingZoomedInView.xaml

<UserControl
x:Class="Stuff.Grouping.GroupingZoomedInView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Stuff.Grouping.Data"
xmlns:telerikGrid="using:Telerik.UI.Xaml.Controls.Grid"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300"
d:DesignWidth="400">

<Grid>
    <Grid.Resources>
        <local:PeopleViewModel x:Key="Model"/>
    </Grid.Resources>
    <telerikGrid:RadDataGrid x:Name="dataGrid" ItemsSource="{Binding Data,Source={StaticResource Model}}" AutoGenerateColumns="False" FontSize="{StaticResource ControlContentThemeFontSize}" SelectionChanged="RadGrid1_SelectedIndexChanged">
        <telerikGrid:RadDataGrid.GroupDescriptors>
            <telerikGrid:DelegateGroupDescriptor>
                <telerikGrid:DelegateGroupDescriptor.KeyLookup>
                    <local:AlpabeticGroupKeyLookup/>
                </telerikGrid:DelegateGroupDescriptor.KeyLookup>
            </telerikGrid:DelegateGroupDescriptor>
        </telerikGrid:RadDataGrid.GroupDescriptors>
        <telerikGrid:RadDataGrid.Columns>
            <telerikGrid:DataGridTextColumn PropertyName="Template"/>
            <telerikGrid:DataGridTextColumn PropertyName="data"/>
            <telerikGrid:DataGridTextColumn PropertyName="info"/>
            <telerikGrid:DataGridTextColumn PropertyName="score"/>
            <telerikGrid:DataGridTextColumn PropertyName="result"/>
            <telerikGrid:DataGridTextColumn PropertyName="repeats"/>
        </telerikGrid:RadDataGrid.Columns>
    </telerikGrid:RadDataGrid>
</Grid>
</UserControl>

GroupingZoomedInView.xaml.cs

public sealed partial class GroupingZoomedInView : UserControl, ISemanticZoomInformation
{
    public void RadGrid1_SelectedIndexChanged(object sender, DataGridSelectionChangedEventArgs e)
    {
        template = (Templates)dataGrid.SelectedItem;
    }

    public void StartViewChangeFrom(SemanticZoomLocation source, SemanticZoomLocation destination)
    {
        source.Item = this.dataGrid.GetDataView().Items.OfType<IDataGroup>().Select(c => c.Key);
    }

    public void StartViewChangeTo(SemanticZoomLocation source, SemanticZoomLocation destination)
    {
        var dataview = this.dataGrid.GetDataView();
        var group = dataview.Items.OfType<IDataGroup>().Where(c => c.Key.Equals(source.Item)).FirstOrDefault();

        var lastGroup = dataview.Items.Last() as IDataGroup;
        if (group != null && lastGroup != null)
        {
            this.dataGrid.ScrollItemIntoView(lastGroup.ChildItems[lastGroup.ChildItems.Count - 1], () =>
            {
                this.dataGrid.ScrollItemIntoView(group.ChildItems[0]);
            });
        }
    }

    public Func<Templates> GetTemplateMethod()
    {
        return () => this.template;
    }
}

Here i need to return the template value to MainPage. How can i do that?

public MainPage()
{
        GroupingZoomedInView gView = new GroupingZoomedInView();
        Func<Templates> method = gView.GetTemplateMethod();
        Templates temp = method();
 }

 public class Templates(){
    public String filename { get; set; }
    public String data { get; set; }
 }

Answer 1

You cannot "return" a value from a class. That only applies to functions. However, you can access the data within a class in several ways.

Use a public field (works, but bad practice)

public string template;

Use a public property (better)

public string Template { get; set; }

Use a public method

public string GetTemplate()
{
    return this.template;
}

For any technique listed here, in your MainPage class you will only be able to access the template value from within the body of a method.

public class MainPage
{
    private GroupingZoomedInView gView;

    public void SomeMethod()
    {
        String temp = gView.GetTemplate();
    }
}

BTW, the same goes for any kind of class. The fact that this one is sealed or partial makes no difference.

---

Update

In a comment, you said you wanted to return a method from a function. In that case, what you need to do use any of the above techniques, but change the return type from string to Func<string> (or some custom delegate type, which I won't go into here).

From member method

private string GetTemplate() 
{
    return this.template;
}

public Func<string> GetTemplateMethod()
{
    return new Func<string>(this.GetTemplate);
}

From a lambda expression

private string template;

public Func<string> GetTemplateMethod()
{
    return () => this.template;
}

From either of these techniques, in your MainPage class you can use the GetTemplateMethod like this.

public class MainPage
{
    private GroupingZoomedInView gView;

    public void SomeMethod()
    {
        Func<string> method = gView.GetTemplateMethod();
        string temp = method(); // executes the method
    }
}