x:Static works as element but not as attribute with statics from project?!?

Question

I'm running Vista RC1 and playing with x:Static in elements and attributes and noticed a behavior that I'm not sure if it is by design or not. Here's the minimal repro:

Start with a Window and let's use a static from the system as its title, using attribute syntax. (The static can come from any referenced assembly in this case, just not from the assembly being compiled):

<Window x:Class="XamlTests.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:System;assembly=mscorlib"
Title="{x:Static Member=s:Environment.CommandLine}"
>
</Window>

This complies and works just as expected, showing the command line in the title of the window. While interesting, this is pretty much useless, so I want to show a string of my own, following the same static pattern, since I don't want to hardcode that string in the XAML as it will be calculated at runtime. For that, I create a static class with the static property:

namespace XamlTests
{
    public static class StaticData
    {
        public static string Hello { get { return "Hello World"; } }
    }
}

Then I reference this as my title, with the proper namespace changes:

<Window x:Class="XamlTests.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:c="clr-namespace:XamlTests;assembly=XamlTests"
Title="{x:Static Member=c:StaticData.Hello}"
>
</Window>

However, this fails to compile with this error:

Window1.xaml(6,5): error MC3050: Cannot find the type 'StaticData'. Note that type names are case sensitive.

Bummer! Does that mean that I can't use my own statics in XAML attributes? That doesn't seem right. On the other hand, if I use element syntax instead of attribute syntax it works, which makes the bug even more interesting:

<Window x:Class="XamlTests.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:c="clr-namespace:XamlTests;assembly=XamlTests"
>
    <Window.Title>
        <x:Static Member="c:StaticData.Hello"/>
    </Window.Title>
</Window>

The end result is exactly what I want and the only downside is the extra markup to get it done.

Sounds like a bug that the compiler can resolve the static call in elements but not in attributes.

The other bummer is that only public classes/methods can be used with x:Static. If the static I want happens to be from the VS-generated Resources.resx file, that class is internal by default and XAML will barf that it is not public.

 

Answer 1

Since the "c:" namespace is a reference to the local assembly -- that is, StaticData and Window1 are both in XamlTests.exe -- you don't need to specify the assembly name on the clr-namespace xmlns.  So this works for me:

    <Window x:Class="XamlTests.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:c="clr-namespace:XamlTests"
        Title="{x:Static Member=c:StaticData.Hello}" >

The behavior still looks like a bug, so we'll investigate, but in the mean time it can simplify your markup.

It should be possible to reference internal types as well.  For example here, I made the StaticData internal.  Are you only seeing a problem when it's in the Resources.resx file?

 

Answer 2

Cool, that worked as long as the property is public, even if the class itself is internal.

With the class generated by the resx it doesn't work because the tool-generated property is also internal. If I manually make the property public then it works, but there's no such option in the resx visual designer. Resgen itself has /publicClass but that option is not exposed in the VS project for resx files.