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Why does structured binding not work as expected on struct?


By : choice
Date : October 14 2020, 02:24 PM
Hope this helps This is a known bug. See https://bugs.llvm.org/show_bug.cgi?id=33236.
Basically, the problem is, the C++17 standard as written specifies that structured binding declaration treats T as a tuple-like type and uses std::tuple_size::value whenever std::tuple_size is defined; but it also specifies that the standard library defines std::tuple_size for all const type T.
code :


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knockout: Binding observable array to click binding does not work as expected


By : Edu OX
Date : March 29 2020, 07:55 AM
This might help you It won't work because this won't be the records array when the click binding invokes the remove method.
You can fix this with using bind:
code :
click: $parent.records.remove.bind($parent.records)

Structured Data Testing Tools following @id references for JSON-LD – Will this work as expected?


By : cbs
Date : March 29 2020, 07:55 AM
may help you .
Of course, I want my schema data to be interpreted as a series of relationships, that's the whole point.

Does structured binding work with std::vector?


By : user1395490
Date : March 29 2020, 07:55 AM
hope this fix your issue Structured binding only works if the structure is known at compile time. This is not the case for the vector.
While you do know the structure of the individual elements, you do not know the number of elements, and that is what you are trying to decompose on in your question. Similarly, you can only use structured bindings on array types where the size is known at compile time. Consider:
code :
void f(std::array<int, 3> arr1,
       int (&arr2)[3],
       int (&arr3)[])
{
    auto [a1,b1,c1] = arr1;
    auto [a2,b2,c2] = arr2;
    auto [a3,b3,c3] = arr3;
}

Failing to work around g++ 7.1 structured binding bug with Boost.Bimap


By : Lâm
Date : March 29 2020, 07:55 AM
Hope that helps I don't think this is something you can work around.
Here's a shorter reproduction:
code :
#include <tuple>

namespace N {
    struct X {
        template <typename T> void get() { }
    };
}

namespace std {
    template <> struct tuple_size<N::X> : integral_constant<size_t, 1> { };
    template <> struct tuple_element<0, N::X> { using type = int; };
}

namespace N {
    template <size_t I> decltype(auto) get(X const&) { return 42; }
}

int main() {
    auto [i] = N::X{};
}
auto [i] = wrap(N::X{});

Decltype of struct data members, using structured binding


By : Manjunath Ghatge
Date : March 29 2020, 07:55 AM
With these it helps I have a template taking a type that is structurally-bindable to two aliases (could be a tuple but also a struct). I need the type of those two variables the aliases point to. , I think you can do something like this:
code :
#include <type_traits>

template <typename T, typename U>
struct Identity {
  using type_first = T;
  using type_second = U;
};

template <typename T>
constexpr auto GetTypes(const T& obj) noexcept {
  const auto& [x, y] = obj;
  return Identity<std::remove_cv_t<decltype(x)>, 
                  std::remove_cv_t<decltype(y)>>{};
}

template <typename T>
void foo(T obj) {
  // T is structurally-bindable with two fields
  constexpr auto Types = GetTypes(obj);
  using t1 = typename decltype(Types)::type_first;
  using t2 = typename decltype(Types)::type_second;

  // t1 is the first type
  // t2 is the second type
}
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