<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock x:Name=’duration’ Text=’{Binding Source={x:Static sys:DateTime.Now},
Converter={fix:Lambda “v=>v.ToString().ToUpper()”}}’/>
</DataTemplate>
</ListBox.ItemTemplate>

Nice article! I really like the concept, but I’m running into a problem using this in one particular scenario. When trying to use the is a DataTemplate for a listbox using the following markup

v.ToString().ToUpper()”}}’/>
<!—->

I get the following error:

Unrecognized property ‘v’ for type ‘WPFix.LambdaExtension’ found while parsing markup extension.

Any suggestions as to why this doesn’t work when used in a DataTemplate?

And.. you said MS is offering a standart alternative?!
Never heard about it, you got me curious, could you elaborate?

And you are making a nw version, cool!

Thanks for your answer!

@Lloyd
Please take a look at the comments at part 2.

I’m trying to make a UIElement visible depending n some boolean, and it throws some mysterious looking exception. I wonder if you could share some light one the problem?

Here is the code which I’m attempting to run:

<Window
x:Class=”VisiTest.Window1″
xlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation”
xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml”
xmlns:pix=”clr-namespace:WPFix;assembly=WPFix”
Title=”Window1″ Height=”300″ Width=”300″>
<StackPanel Orientation=”Vertical”>
<CheckBox x:Name=”cVisi” Content=”Button is visible”/>

<Button Content=”OK”
Visibility=”{Binding IsChecked, ElementName=cVisi, Converter={pix:Lambda ‘b=>b?Visibility.Visible:Visibility.Collapsed’}}”/>
</StackPanel>
</Window>

Thus it’s not the most elegant or convenient syntax, but at least it works. I did it in such a way that it’s only required if a value could be null; therefore if the ConverterParameter isn’t provided it defaults to its original behavior.

Here are the relevant changes:

public object Convert( object value, Type targetType, object parameter, System.Globalization.CultureInfo culture ) {
if ( this.ForwardOperation == null ) {
if ( value == null && parameter == null )
return Binding.DoNothing;
ForwardOperation = ConstructOperation( this.Forward, value, parameter as Type, targetType );
}
try {
return this.ForwardOperation.DynamicInvoke( value );
} catch {
return Binding.DoNothing;
}
}

private Delegate ConstructOperation( string code, object value, Type valueType, Type targetType ) {
int opi = code.IndexOf( “=>” );
if ( opi ” );
string param = code.Substring( 0, opi );
string body = code.Substring( opi + 2 );
ParameterExpression p = Expression.Parameter( valueType != null ? valueType : value.GetType(), param );
LambdaExpression lambda = DynamicExpression.ParseLambda( this.TypeResolver, new ParameterExpression[] { p }, targetType, body, value );
return lambda.Compile();
}