Why initializer list do not move elements?

Asked Jun 01 '17 at 10:03

Active Jun 01 '17 at 10:03

Viewed 72 times

I have been surprised to find that this simple exemple does not compile:

#include <memory>
#include <vector>
#include <array>
using vt = std::vector<std::unique_ptr<int>>;
using at = std::array<std::unique_ptr<int>,1>;
int main(){
    auto a = at{std::make_unique<int>(10)}; //compile fine
    auto v = vt{std::make_unique<int>(10)}; //error
}

Why is there no vector constructor taking as argument type initializer_list<T>&& ?

asked Jun 01 '17 at 10:03

Oliv

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Having such a constructor won't do you any good either way. Once you have an initializer list, copying the list doesn't copy the elements. The compiler is complaining because it can't populate the list to begin with. – StoryTeller - Unslander Monica Jun 01 '17 at 10:06
`std::vector` elements must be "CopyAssignable", but `unique_ptr` isn't. – alain Jun 01 '17 at 10:08
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@alain - That is incorrect. The restrictions on the type held in the vector depend on how the vector is used (since C++11). You can have a vector of `unique_ptr`s just fine. – StoryTeller - Unslander Monica Jun 01 '17 at 10:10
Oh yes, you're right @StoryTeller, thanks. – alain Jun 01 '17 at 10:15

Why initializer list do not move elements?

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