c# - What is best practise for IValueConverter? -

• what best practise ivalueconverter?
• is ok put exception in convert method or should return "something"?

here example:

[valueconversion(typeof(float), typeof(string))] public class percentconverter : ivalueconverter {     public object convert(object value, type targettype, object parameter, cultureinfo culture)     {         if (value == null || string.isnullorempty(value.tostring()))             return string.empty;          if (value float) //edited support cultureinfo.currentculture,             return string.format(culture, "{0:n}{1}", ((float)value) * 100, "%");          //** ok put exception here or should return "something" here? **         throw new exception("can't convert " + value.gettype().name + ". expected type if float.");     }      public object convertback(object value, type targettype, object parameter, cultureinfo culture)     {         throw new notsupportedexception("converting not implemented in " + this.gettype());     } } 

if fail convert (malformed values, types, ...), return dependencyproperty.unsetvalue.

it indicates converter produced no value , binding uses fallbackvalue, if available, or default value instead.

also, should convert data culture-specific conversion or invariant conversions on safe side.