I have just looked at an example from Microsoft Social Network on how to use Application Settings namely this one:

public bool IsUSer(SettingsProperty Setting)
        {
            bool flag = Setting.Attributes[typeof(UserScopedSettingAttribute)] is UserScopedSettingAttribute;
            bool flag1 = Setting.Attributes[typeof(ApplicationScopedSettingAttribute)] is ApplicationScopedSettingAttribute;

            if (flag && flag2)
            {
                throw new ConfigurationErrorsException(SR.GetString("BothScopeAttributes"));
            }
            if (!flag && !flag2)
            {
                throw new ConfigurationErrorsException(SR.GetString("NoScopeAttributes"));
            }
            return flag;
        }

This checks to see if the Setting is both User and Application Scoped or neither. Is it even possible that these two situations can occur. Surely the API would not allow this to happen in the first place. Should we be checking for this or is this example a little over the top. I know this is more a discussional rant but really, surely this can’t really happen?

Link to Example: https://social.msdn.microsoft.com/Forums/en-US/4c0d2eae-2f0b-41c8-bb60-c4b0ffd3cd0b/how-to-retrieve-usersettings-v-defaultsettings-c-vbe2008?forum=netfxbcl

Thanks
Danny

>Solution :

[UserScopedSetting] and [ApplicationScopedSetting] are attributes so you might use them like this:

public class MyUserSettings : ApplicationSettingsBase
{
    [UserScopedSetting()]
    [DefaultSettingValue("white")]
    public Color BackgroundColor
    {
        get
        {
            return ((Color)this["BackgroundColor"]);
        }
        set
        {
            this["BackgroundColor"] = (Color)value;
        }
    }
}

(Source for above code)

If you refer to this question, you’ll see that it isn’t possible to prevent two attributes occurring together. So, the code you have shown is actually protecting against one of these two scenarios:

1 – Both attributes are applied:

public class MyUserSettings : ApplicationSettingsBase
{
    [UserScopedSetting()]
    [ApplicationScopedSetting()]
    [DefaultSettingValue("white")]
    public Color BackgroundColor
    {
        get
        {
            return ((Color)this["BackgroundColor"]);
        }
        set
        {
            this["BackgroundColor"] = (Color)value;
        }
    }
}

2 – Neither attribute is applied:

public class MyUserSettings : ApplicationSettingsBase
{
    [DefaultSettingValue("white")]
    public Color BackgroundColor
    {
        get
        {
            return ((Color)this["BackgroundColor"]);
        }
        set
        {
            this["BackgroundColor"] = (Color)value;
        }
    }
}

So ultimately it is checking that exactly one of these two attributes is applied.