How to initialize c++/cx class with aggregate initialization? - windows-runtime

Question

I have this ref class:
namespace N
{
public ref class S sealed
{
public:
property Platform::String^ x;
};
}
How do I initialize it in place with the aggregate initializer?
I have tried:
N::S s1 = { %Platform::String(L"text") };
but the compiler says
error C2440: 'initializing': cannot convert from 'initializer list' to
'N::S'
Also:
N::S s1 { %Platform::String(L"text") };
and the error is:
error C2664: 'N::S::S(const N::S %)': cannot convert argument 1 from
'Platform::String ^' to 'const N::S %'
This works greatly with the standard c++ like this:
struct T
{
wstring x;
};
T x { L"test" };
I do not want to use a constructor here.

Answer 1

I assume you mean you don't want a public constructor on the projected WinRT type -- no problem, you can use the internal keyword to mean "public inside C++ but not exposed through interop". That means you can even use native C++ types for your parameters if you like:
namespace Testing
{
public ref class MyTest sealed
{
public:
property String^ Foo {
String^ get() { return m_foo; }
void set(String^ value) { m_foo = value; }
}
internal:
// Would not compile if it was public, since wchar_t* isn't valid
MyTest(const wchar_t* value) { m_foo = ref new String(value); }
private:
String^ m_foo;
};
}
MainPage::MainPage()
{
// Projected type does NOT have this constructor
Testing::MyTest t{ L"Hello" };
OutputDebugString(t.Foo->Data());
t.Foo = "\nChanged";
OutputDebugString(t.Foo->Data());
}
Also you don't need to have the private variable to hold the string -- you could just use the auto-property as in your original code -- but I prefer to be explicit. It also means that if you needed to access the string a lot from within your C++ code you could provide an internal accessor function and not have to go through a vtable call to get at it.