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Why can't I construct a gsl::span with a brace-enclosed initializer list


Why can't I construct a gsl::span with a brace-enclosed initializer list

By : Brian Locke
Date : November 22 2020, 09:00 AM
This might help you When you call the vector version, the initializer list is used to create a temporary std::vector, which is then passed to the function by const reference. This is possible, because std::vector has a constructor, that takes an std::initializer_list as an argument.
However, gsl::span doesn't have such a constructor and as {1,2,3} doesn't have a type, it also can't be accepted by the templated constructor you mentioned (besides the fact, that std::initializer_list wouldn't satisfy the container concept anyway).
code :
func(std::array<int,3>{ 0,1,2,3 });
func({ 0,1,2,3 });
gsl::span<const int> data{ 0,1,2,3 };
func(data);


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brace-enclosed initializer list

brace-enclosed initializer list


By : Luke A
Date : March 29 2020, 07:55 AM
I wish this helpful for you assuming I have an object similar to this one: , I believe it is safe according to 8.5.1/7 :
Why can't I construct a queue/stack with brace-enclosed initializer lists? (C++11)

Why can't I construct a queue/stack with brace-enclosed initializer lists? (C++11)


By : Lexiandro
Date : March 29 2020, 07:55 AM
With these it helps I don't think it really has anything to do with being container adapters rather than containers (though I'll admit I'm uncertain exactly why the correct constructor is omitted).
When you use a braced initializer list with std::vector, you're using this (new in C++11) constructor:
code :
vector(initializer_list<T>, const Allocator& = Allocator());
explicit queue(const Container&);
explicit queue(Container&& = Container());
template <class Alloc> explicit queue(const Alloc&);
template <class Alloc> queue(const Container&, const Alloc&);
template <class Alloc> queue(Container&&, const Alloc&);
template <class Alloc> queue(const queue&, const Alloc&);
template <class Alloc> queue(queue&&, const Alloc&);
#include <deque>
#include <initializer_list>
#include <iostream>

template <class T, class container=std::deque<T> >
class myqueue {
    container data;
public:
    explicit myqueue(std::initializer_list<T> t) : data(t) {}
    void pop() { data.pop_front(); }
    T front() const { return data.front(); }
    bool empty() const { return data.empty(); }
};

int main(){
    myqueue<int> data {1, 2, 3, 4};
    while (!data.empty()) {
        std::cout << data.front() << "\n";
        data.pop();
    }
    return 0;
}
1
2
3
4
std::stack<int> data(std::vector<int>{1,2,3,4});
could not convert from <brace-enclosed initializer list>

could not convert from <brace-enclosed initializer list>


By : Ashokkumar
Date : March 29 2020, 07:55 AM
I wish this helpful for you You need to remove the extra {} if you want to use a plain array F{(void(Is),j)...}. Or change it to std::array F like you said.
A plain array simply uses {} for initialization, however and std::array is an aggregate which contains an array, so it uses the double braces.
Could not convert from '<brace-enclosed initializer list> to

Could not convert from '<brace-enclosed initializer list> to


By : Rafael Bitencourt
Date : March 29 2020, 07:55 AM
Hope this helps I know that has a lot of questions similar, but I saw them and none of them helped me, I think is that because mine is kind of different, and at the same time weird. , You must initialize the 'b' like this:
Error: could not convert '<brace-enclosed initializer list>()' from '<brace-enclosed initializer list>' to '

Error: could not convert '<brace-enclosed initializer list>()' from '<brace-enclosed initializer list>' to '


By : Swen
Date : March 29 2020, 07:55 AM
it should still fix some issue , Rows is 2. So the size of
code :
Vec<T, Cols> data[Rows];
: data{Vec<T, Cols>(s)} {} 
       // initializer has only one element
constexpr Vec(const T& s)
        : data{s} {}
constexpr Vec()
    :data {} {}
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