如何创建一个带有自定义分配器的std ::函数？ [英] How can I create a std::function with a custom allocator?

问题描述

保存一些代码让我说我有一个名为 MyAlloc 的自定义分配器，我已成功使用 std :: vector< int> 如下：

To save some code lets say I have a custom allocator named MyAlloc which I have successfully used with a std::vector<int> as follows:

std::vector<int,MyAlloc<int>> vec;

现在我想使用自定义分配器在std ::函数中保存一个lambda，是吗？

now I want to save a lambda in a std::function using the custom allocator, how do I do it?

我的失败尝试：

int i[100];
std::function<void(int)> f(MyAlloc<void/*what to put here?*/>{},[i](int in){
    //...
});

推荐答案

根据标准， a href =http://en.cppreference.com/w/cpp/memory/allocator_arg =nofollow>标签类型作为第一个参数，表示您要使用自定义分配器： / p>

According to the standard, you need to give a tag type as the first argument to indicate that you want to use a custom allocator:

std::function<void(int)> f(std::allocator_arg, MyAlloc<char>{}, [i](int in){
    //...
});

正如 @ Casey 和 @ Potatoswatter 在注释中，给分配器的模板参数类型无关紧要，因为它是一个对象类型。所以 char 在这里很好。

As pointed out by @Casey and @Potatoswatter in the comments, the template argument type given to the allocator does not matter, as long as it's an object type. So char is fine here.

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