CODEWITHSUNDEEP
c#wpfxamlmarkup-extensions
Benlitz
Benlitz

Reputation: 2002

Markup extension naming

I'm pretty sure the answer is no, but is there a way to name a markup extension differently from the class that implements it?

I would like to make a markup extension that has a relatively short name:

<TextBlock Text="{my:Ext}"/>

but I would like to give it a different (longer) name on C# side:

public class MySpecificMarkupExtension : MarkupExtension

The only information I found about naming is on this page and the *Extension pattern, which is not what I want to achieve. I was hoping an Attribute would exists that allow me to do this:

[SomeAttribute("Ext")]
public class MySpecificMarkupExtension : MarkupExtension

But I've checked most of the attributes in the System.Windows.Markup namespace and there is no such attribute unfortunately.

Is there any solution to this problem?

Upvotes: 1

Views: 536

Answers (1)

dev hedgehog
dev hedgehog

Reputation: 8791

The answer is as you may have already assumed NOPE. There is no such class attribute. None that I know.

Since you mentioned you have a large amount of exceptions and you would like to keep xaml as simple as possible how about you have just one extension that calls others based on a key.

Its like hiding all those extension behind a certain key.

Take a look at this:

public class MyExtExtension : MarkupExtension
{
    public string Output
    {
        get; set;
    }

    public MyExtExtension(string output)
    {
        this.Output = output;
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return this.Output;
    }
}

public class MarkupExtensionChooser : MarkupExtension
{
    public string Key
    {
        get;
        set;
    }

    public StringList Param
    {
        get; set;
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        if (this.Key.Equals("ext"))
        {
            return new MyExtExtension(this.Param.Data[0]).ProvideValue(serviceProvider);
        }

        if (this.Key.Equals("ext123"))
        {
            // Custom Logic
        }

        if (this.Key.Equals("ext123123123"))
        {
            // Custom Logic
        }

        if (this.Key.Equals("ext123123123"))
        {
            // Custom Logic
        }

        if (this.Key.Equals("ext12121412423"))
        {
            // Custom Logic
        }

        return this;
    }
}

public class StringListTypeConverter : TypeConverter
{
    public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
    {
        if (value is string)
        {
            string val = (string)value;
            return new StringList(val.Split(','));
        }

        return null;
    }
}

[TypeConverter(typeof(StringListTypeConverter))]
public class StringList
{
    public string[] Data
    {
        get; set;
    }

    public StringList(string[] data)
    {
        this.Data = data;
    }
}

I ended up creating that "chooser class" which can also accept parameters and based on the key I return the necessary extension.

The TypeConverter is just there to allow having Param="args1,args2,args3" in xaml.

This is how my example in main window looks like:

<TextBox Text="{local:MarkupExtensionChooser Key=ext, Param='hello,world'}"/>

Hello will be displayed in TextBox since I pass param[0] to MyExtExtension.

It works fine for me but I am not sure if you can use something like this.

The idea is pretty simple however in the end its a bit of wpf tricking behind this and if you cannot follow let me know. I ll gladly assist you any futher.

Upvotes: 2

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