Windows 8 introduces a number of innovations in the way information is delivered to developers. Microsoft would like to know how well these are working for you, and where they can make further changes to improve your experience.
To review the site before you complete the survey, visit the Windows 8 Dev Center. In particular, have a look at the section called Learn to build Metro style apps.
A few questions in the survey are about about how the Windows 8 site experience compares to the iOS and Android sites. If you aren’t an experienced iOS or Android developer, feel free to skip these parts. But, if you’ve made apps for those platforms, or if you’d like to compare site features based on just a browse through those sites, Microsoft would like to hear your opinion.
The survey will be available here until July 27, 2012.
The C# Language Specification states on §7.5.1.2 that “(…) the expressions or variable references of an argument list are evaluated in order, from left to right (…)”.
So, when this code is compiled with the C# 4.0 compiler:
static void M(
int x = 10,
int y = 20,
int z = 30)
{
Console.WriteLine(
"x={0}, y={1}, z={2}", x, y, z);
}
static void Main(string[] args)
{
int a = 0;
M(++a, z: ++a);
}
and run, this unexpected output is obtained:
x=2, y=20, z=1
In fact, fixing this compiler flaw was the cause of one of the few breaking changes introduced in C# 5.0.
Using the 5.0 compiler, the expected result is obtained:
x=1, y=20, z=2
To avoid this type of surprises, expression evaluation should be avoided in argument lists.
With this code:
int a = 0;
int i = ++a;
int j = ++a;
M(i, z: j);
the same result is obtained for both C# 4.0 and C# 5.0:
x=1, y=20, z=2
(This content was written based on Silverlight for Windows Phone, but might be valid for generic Silverlight.)
There are a many articles on MSDN (and all over the Internet) about globalization and localization of Silverlight applications in general and specifically Windows Phone 7 applications but I haven’t found any that uses a value converter.
If you read the documentation for the IValueConverter interface, you can see that both in the Convert and ConvertBack methods have a culture parameter of type CultureInfo.
And why would we need the culture for the conversion? Imagine the application is a shop that shows prices in more than one currency. Or the application is a currency converter.
The culture parameter is used as the culture of the conversion. Any place inside the Convert or ConvertBack methods where a CultureInfo or IFormatProvider instance is need, the culture parameter should be used:
public class MoneyValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value != null)
{
return string.Format(culture, "{0:C}", value);
}
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
The value of the culture parameter is determined in the following order:
-
-
The first case is very straightforward:
<TextBlock Text="{Binding Euros, Converter={StaticResource MoneyValueConverter}, ConverterCulture=pt-PT}" />
<TextBlock Text="{Binding Dollars, Converter={StaticResource MoneyValueConverter}, ConverterCulture=en-US}" />
But that should only be used when the culture of the conversion differs form the application culture or has an explicit value. The second case is the most frequently used and that’s where things get complicated. The value of the Language property of an element, if not explicitly set, is inherited from its container. In the case of Windows Phone 7, up to the phone application frame. And it’s never null.
I was expecting that the value of the Language property of the phone application frame would reflect the value of the current culture but, as far as I can tell, it’s always en-US.
So, if, unless explicitly set, the language is always en-US. How to specify which culture to use inside the value converter methods? The current culture could be used, but how to know if the language has been changed or the culture has been explicitly specified?
The solution is setting the language on the phone application frame and always to be able to use the culture parameter inside the converter methods:
this.RootFrame = new PhoneApplicationFrame
{
Language = XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.Name)
};
The correct way to get the XML language would be to use the IetfLanguageTag property of the current culture, but that property is not available on Silverlight.
As far as I could find, you won’t get into trouble unless you’re dealing with Chinese cultures. But if you’re like me, you’ll probably be publishing your applications worldwide.
It’s not an hard problem to solve, though. A couple of extension method can solve it:
public static class CultureInfoExtensions
{
public static XmlLanguage GetXmlLanguage(this CultureInfo culture)
{
return XmlLanguage.GetLanguage(culture.GetIetfLanguageTag());
}
public static string GetIetfLanguageTag(this CultureInfo culture)
{
switch (culture.Name)
{
case "zh-CHT":
return "zh-Hant";
case "zh-CHS":
return "zh-Hans";
default:
return culture.Name;
}
}
}
And now the language of the root phone application frame can be properly initialized:
// Avoid double-initialization
// Do not add any additional code to this method
private void InitializePhoneApplication()
{
Debug.WriteLine("{0} >> InitializePhoneApplication", DateTime.Now.Ticks);
if (this.phoneApplicationInitialized)
{
return;
}
// Create the frame but don't set it as RootVisual yet; this allows the splash
// screen to remain active until the application is ready to render.
this.RootFrame = new RadPhoneApplicationFrame
{
Language = CultureInfo.CurrentUICulture.GetXmlLanguage()
};
this.RootFrame.Navigated += CompleteInitializePhoneApplication;
// Handle navigation failures
this.RootFrame.NavigationFailed += RootFrame_NavigationFailed;
// Ensure we don't initialize again
this.phoneApplicationInitialized = true;
}
Resources: