value struct not initialized in WinRT

Question

For whatever reason, the initialized value of a value struct defined in Windows Runtime Component is ignored in the app (C#).

CX/C++:

namespace RuntimeComponent1
{
    public value struct Foo {
        bool flag1 = true;
        bool flag2 = false;
    };
}

C#

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();

        var settings = new RuntimeComponent1.Foo();
        Debug.WriteLine(settings.flag1); // Output: False
        Debug.WriteLine(settings.flag2); // Output: False
    }
}

Notice that flag1 should be True but instead it is False. Why? !

Edit: As suggested by @HansPassant, create a ticket for this: https://connect.microsoft.com/VisualStudio/feedback/details/2702659 If you also think this is a problem. Please help up voting it.

Not all languages support constructors for value types (e.g. JS). Therefore, WinRT does not support constructors for value types. (More accurately, constructors for value types are not projected.) — Raymond Chen, May 13 '16 at 14:34
@RaymondChen kind of make sense. I guess I am more upset about that fact that there is no warnings/errors on this than the fact that it is not supported. — Yuchen, May 13 '16 at 14:43
Feel better about it by reporting this at connect.microsoft.com — Hans Passant, May 13 '16 at 15:14

score 1 · Accepted Answer · answered Aug 10 '16 at 13:11

I have got an email update from Microsoft VC++ team after posting the issue on Microsoft connect https://connect.microsoft.com/VisualStudio/feedback/details/2702659

Thank you for reporting this issue. The next release of the Visual C++ Compiler Toolset will issue an error when a member of a value class has a default member initializer.

value struct not initialized in WinRT

1 Answers1